JP2011021077A - Self-adhesive film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a self-adhesive film that has low adhesive force immediately after being stuck under pressure and can be easily re-stuck without leaving a removal trace, and that shows an increase in the adhesive force with lapse of time after pressure-sticking and can be firmly adhered to an adherend. <P>SOLUTION: The self-adhesive film 1 comprises a self-adhesive layer 3 on a film substrate 2, wherein the self-adhesive layer 3 contains a self-adhesive polyurethane having a weight-average molecular weight of ≤5.6×10<SP>4</SP>obtained by chain-extending a prepolymer with diamine, the prepolymer obtained by allowing a diol as a condensate of 4-8C alkane diol and adipic acid to react with isophorone diisocyanate. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an adhesive film.

  Conventionally, as an adhesive film, what uses the acrylic polymer which has strong adhesive force for an adhesive is used abundantly. Such a pressure-sensitive adhesive film exhibits a strong adhesive force, but it is difficult to re-apply when the attaching position is wrong at the time of attaching or air is involved. Further, a phenomenon of peeling or stopping (referred to as zipping, slip stick, etc.) easily occurs at the time of peeling, and a peeling mark is likely to be made.

  On the other hand, Patent Document 1 discloses pressure-sensitive adhesive sheets using a polyurethane having a specific storage elastic modulus and having a polycarbonate structure as a pressure-sensitive adhesive. Such pressure-sensitive adhesive sheets are said to exhibit excellent adhesiveness while being highly elastic and tack-free (meaning that they are substantially non-sticky).

Japanese Patent Laid-Open No. 2005-154782

  However, in the field of decorative adhesive films, it is necessary that not only the re-sticking but also the peeling marks are inconspicuous, but the conventional adhesive films leave marks after being peeled once or a plurality of times. There is a problem.

  Therefore, the present invention has a low adhesive force immediately after pressure bonding, and can be easily reattached with almost no trace of peeling off, and the adhesive force improves with the passage of time after pressure bonding, An object is to provide an adhesive film that can be firmly bonded to an adherend.

The present invention is an adhesive film comprising an adhesive layer on a film substrate, wherein the adhesive layer is obtained by reacting a diol obtained by condensing an alkanediol having 4 to 8 carbon atoms and adipic acid with isophorone diisocyanate. Provided is an adhesive film which is a layer containing an adhesive polyurethane having a weight average molecular weight of 5.6 × 10 ⁴ or less, in which a prepolymer is chain-extended with diamine. Such an adhesive film has a low adhesive force immediately after pressure bonding, and can be easily reattached. In addition, after a predetermined time has passed since the pressure bonding, the adhesive strength is excellent, and it adheres firmly to the adherend. Furthermore, almost no peeling marks remain when reapplying. Therefore, it can be suitably used as a decorative pressure-sensitive adhesive film, particularly as a decorative pressure-sensitive adhesive film in which peeling marks such as high-gloss decoration and metal appearance decoration tend to remain.

  In the pressure-sensitive adhesive film of the present invention, the alkanediol having 4 to 8 carbon atoms is preferably 3-methyl-1,5-pentanediol or 2-methyl-1,3-propanediol. Such an adhesive film has the above-described effects more effectively, and is excellent in hydrolysis resistance and weather resistance.

  A preferable example of the film substrate is a resin film substrate because of its excellent flexibility.

  According to the present invention, the adhesive force is low immediately after pressure bonding, and it can be easily reattached with almost no trace of peeling off, and the adhesive strength improves as time passes after pressure bonding. An adhesive film that can be firmly bonded to an adherend is provided.

1 is a schematic cross-sectional view of an adhesive film that is a preferred embodiment of the present invention.

The pressure-sensitive adhesive film according to the present embodiment is a pressure-sensitive adhesive film including a pressure-sensitive adhesive layer on a film substrate, and the pressure-sensitive adhesive layer includes a diol obtained by condensing an alkanediol having 4 to 8 carbon atoms and adipic acid, and isophorone diisocyanate. This is a layer containing an adhesive polyurethane having a weight average molecular weight of 5.6 × 10 ⁴ or less, in which a prepolymer obtained by reacting is chain-extended with diamine.

  Such a pressure-sensitive adhesive film has a low adhesive force immediately after pressure bonding (hereinafter, referred to as “initial adhesive force” in some cases), and the adhesive force increases with time. It becomes bonded to the body (hereinafter, the fixed adhesive force is sometimes referred to as “normal adhesive force”). Here, the predetermined time until the adhesive force becomes a constant value varies depending on the composition of the pressure-sensitive adhesive layer, the form of the adherend, temperature, humidity, etc., but is generally under standard conditions (temperature 21 ° C., humidity 65%). ) Within 48 hours. Therefore, the normal state adhesive force can be measured by measuring the adhesive force 48 hours after pressure bonding under standard conditions.

  The adhesive strength of the adhesive film is, for example, that the adhesive film is cut to a width of 25 mm and a length of 200 mm, and a 2 kg roller is reciprocated on the adherend under standard conditions, and this is pressure-bonded. It can be measured by peeling with a tensile tester at a speed of 300 mm / min.

  The initial adhesive force of the pressure-sensitive adhesive film is preferably 10 N / 25 mm or less, more preferably 5 N / 25 mm or less. According to such an adhesive film, it is easy to re-paste and scars are hardly seen. The initial adhesive force is preferably 0.3 N / 25 mm or more, more preferably 0.5 N / mm or more, and further preferably 1 N / mm or more. If the initial adhesive force is less than 0.3 N / 25 mm, temporary attachment or the like is difficult, and workability tends to be inferior.

  The normal adhesive force of the pressure-sensitive adhesive film is preferably 10 N / 25 mm or more, more preferably 13 N / 25 mm or more, further 15 N / 25 mm or more, and particularly 20 N / 25 mm or more. Such a pressure-sensitive adhesive film can be effectively used practically, and is less likely to be peeled off even during long-term use.

  FIG. 1 is a schematic cross-sectional view of an adhesive film which is a preferred embodiment of the present invention. An adhesive film 1 shown in FIG. 1 includes an adhesive layer 3 on a film substrate 2. When the adhesive film 1 is adhered to the adherend, for example, the adherend and the adhesive layer 3 are in contact with each other, and from the back surface of the film base 2 (the surface opposite to the surface in contact with the adhesive layer 3). Press.

(Adhesive layer)
The pressure-sensitive adhesive layer has a weight average molecular weight of 5.6 × 10, obtained by chain-extending a prepolymer obtained by reacting a diol obtained by condensing an alkanediol having 4 to 8 carbon atoms and adipic acid with isophorone diisocyanate. It is a layer containing ⁴ or less adhesive polyurethane. The adhesive layer may further contain additives such as a plasticizer, a filler, a tackifier, and a colorant.

  Examples of the alkanediol having 4 to 8 carbon atoms include 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 2,3-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, 2-methyl-1,4-butanediol, 2-ethyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 1,6-hexanediol, 2 -Methyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,4-butanediol, 2,2-dimethyl-1,4-butanediol, 2,3-dimethyl -1,4-butanediol, 2-propyl-1,3-propanediol, 2-methyl-2-ethyl-1,3-propanediol, 1,7-heptanediol, 2-methyl 1,6-hexanediol, 3-methyl-1,6-hexanediol, 2-ethyl-1,5-pentanediol, 3-ethyl-1,5-pentanediol, 2,3-dimethyl-1,5- Pentanediol, 2,4-dimethyl-1,5-pentanediol, 2,2-dimethyl-1,5-pentanediol, 3,3-dimethyl-1,5-pentanediol, 2-propyl-1,4- Butanediol, 2-methyl-3-ethyl-1,4-butanediol, 2-butyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2-methyl-2-propyl- 1,3-propanediol, 1,8-octanediol, 2-methyl-1,7-heptanediol, 3-methyl-1,7-heptanediol, 4-methyl-1,7-hepta Diol, 2-ethyl-1,6-hexanediol, 3-ethyl-1,6-hexanediol, 2,2-dimethyl-1,6-hexanediol, 2,3-dimethyl-1,6-hexanediol, 2,4-dimethyl-1,6-hexanediol, 2,5-dimethyl-1,6-hexanediol, 3,3-dimethyl-1,6-hexanediol, 3,4-dimethyl-1,6-hexane Diol, 2-propyl-1,5-pentanediol, 3-propyl-1,5-pentanediol, 2-ethyl-2-methyl-1,5-pentanediol, 2-ethyl-3-methyl-1,5 -Pentanediol, 2-ethyl-4-methyl-1,5-pentanediol, 3-ethyl-2-methyl-1,5-pentanediol, 3-ethyl-3-methyl-1,5-pent Tandiol, 3-ethyl-4-methyl-1,5-pentanediol, 2,2,3-trimethyl-1,5-pentanediol, 2,3,3-trimethyl-1,5-pentanediol, 2,3 , 4-trimethyl-1,5-pentanediol, 2-butyl-1,4-butanediol, 2-propyl-2-methyl-1,4-butanediol, 2-propyl-3-methyl-1,4- Butanediol, 2,2-diethyl-1,4-butanediol, 2,3-diethyl-1,4-butanediol, 2-ethyl-2,3-dimethyl-1,4-butanediol, 2-pentyl- Examples include 1,3-propanediol, 2-butyl-2-methyl-1,3-propanediol, 2-ethyl-2-propyl-1,3-propanediol, and the like. Of these, at least one of the hydroxyl groups is preferably bonded to the primary carbon, and more preferably all of the hydroxyl groups are bonded to the primary carbon. By having such an alkanediol skeleton in the structural unit, the hydrolysis resistance of the adhesive polyurethane is improved, and an adhesive film having a layer containing the adhesive polyurethane becomes excellent in weather resistance. Further, since the effects of the present invention can be obtained more effectively, as the alkanediol having 4 to 8 carbon atoms, 3-methyl-1,5-pentanediol and 2-methyl-1,3-propanediol are more preferable. preferable.

  Examples of the diol obtained by condensing an alkanediol having 4 to 8 carbon atoms and adipic acid (hereinafter sometimes referred to as “polyester-based diol”) include diols represented by the following general formula (1).

In the general formula (1), R ¹ represents an alkylene group having 4 to 8 carbon atoms, and n represents an integer of 1 or more. Examples of the alkylene group include alkylene groups corresponding to the above-exemplified alkanediols. N is preferably an integer of 4 to 20. When n is equal to or less than the upper limit of the above range, the initial adhesive force can be sufficiently suppressed, and the remaining of the peeling mark can be further reduced. Moreover, there exists a tendency for normal state adhesive force to improve further by being more than a lower limit.

  The weight average molecular weight of the polyester diol is preferably about 2,000 to about 10,000. When the weight average molecular weight is within the above range, the initial adhesive force and the normal adhesive force can be improved in a balanced manner.

  The polyester-based diol is a condensate of an alkanediol having 4 to 8 carbon atoms and adipic acid, but the polyester-based diol in the present invention is obtained from a raw material in place of an alkanediol having 4 to 8 carbon atoms or adipic acid, Polyester diols having the same chemical structure as the condensate are also included. That is, as a polyester-based diol, as long as it has the same chemical structure as a polyester-based diol obtained by a condensation reaction of an alkanediol having 4 to 8 carbon atoms and adipic acid, an alkanediol having 4 to 8 carbon atoms. A polyester-based diol that can be obtained by a reaction of adipic acid derivatives (adipic acid ester or adipic acid dichloride) or the like can also be used.

  The dehydration condensation reaction between an alkanediol having 4 to 8 carbon atoms and adipic acid can be performed, for example, by heating the alkanediol having 4 to 8 carbon atoms and adipic acid in a nitrogen atmosphere. In the reaction, the reaction is preferably performed such that the number of equivalents of the alkanediol having 4 to 8 carbon atoms is larger than the number of equivalents of adipic acid. The number of equivalents of the alkanediol having 4 to 8 carbon atoms is preferably greater than 1 and less than or equal to 5, more preferably greater than 1 and less than or equal to 3, more preferably greater than 1 and less than or equal to 2, assuming that the equivalent number of the polyester diol is 1. . As a preferred reaction example, 100 parts by mass of 2-methyl-1,3-propanediol and 145 parts by mass of adipic acid are put into a flask, heated and stirred at about 200 ° C., and water produced by the condensation reaction is removed. Thus, a reaction for obtaining a polyester-based diol can be mentioned by advancing the reaction. The number average molecular weight of the polyester diol obtained by such a reaction is about 2000.

  The prepolymer is a prepolymer obtained by reacting a polyester diol and isophorone diisocyanate, and such a prepolymer has a structure represented by the following general formula (2) or the following general formula (3). In addition, although the hydroxyl group derived from a polyester-type diol or the isocyanate group derived from isophorone diisocyanate exists in the terminal of a prepolymer, Preferably, the terminal is an isocyanate group derived from isophorone diisocyanate.

In General Formula (2) and General Formula (3), R ¹ and n are as defined above, and m represents an integer of 1 or more. m is preferably 2 to 10. When m is equal to or less than the upper limit of the above range, the initial adhesive force can be sufficiently suppressed, and the remaining of the peeling mark can be further reduced. Moreover, there exists a tendency which normal state adhesive force improves further by being more than a lower limit.

  The weight average molecular weight of the prepolymer is preferably from about 3,000 to about 20,000. When the weight average molecular weight is within the above range, the initial adhesive force and the normal adhesive force can be improved in a balanced manner.

  The prepolymer is a reaction product obtained by reacting a polyester diol and isophorone diisocyanate, but the prepolymer according to the present embodiment is equal to the above reaction product obtained from a raw material in place of the polyester diol or isophorone diisocyanate. Those having a chemical structure are also included. That is, as a prepolymer, as long as it has the same chemical structure as a prepolymer obtained by reacting a polyester diol and isophorone diisocyanate, a reaction between a dicarbonate and a diamine, or a chloroformate and a diamine A prepolymer that can be obtained by the above reaction can also be used.

  The reaction between the polyester diol and isophorone diisocyanate can be performed, for example, by mixing the polyester diol and isophorone diisocyanate in an organic solvent under a nitrogen atmosphere. A urethanization catalyst (for example, a tin-based catalyst such as dibutyltin laurate) may be added to the reaction system. In the reaction, the reaction is preferably carried out so that the equivalent number of isophorone diisocyanate is larger than the equivalent number of the polyester diol. The number of equivalents of isophorone diisocyanate is preferably greater than 1 and less than or equal to 5, more preferably greater than 1 and less than or equal to 3, with the number of equivalents of the polyester diol being 1. The molecular weight of the prepolymer and the isocyanate group content% in the prepolymer can be changed by appropriately adjusting the equivalent number ratio. The prepolymer obtained by such a reaction can be chain-extended with diamine without isolation from the reaction solution.

  Adhesive polyurethane is obtained by chain-extending a prepolymer with diamine. The diamine is not particularly limited as long as the prepolymer can be chain-extended, and ethylenediamine, propylenediamine, hexamethylenediamine, isophoronediamine, dicyclohexylmethane-4,4-diamine, 2-hydroxyethylethylenediamine, 2-hydroxyethyl. Propylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, di-2-hydroxypropylethylenediamine and the like can be used. As the diamine, a diamine having a cyclic saturated hydrocarbon group is preferable, and isophorone diamine is more preferable. Thereby, the difference between the initial adhesive force and the normal adhesive force of the pressure-sensitive adhesive film is increased, and the effects of the present invention are more remarkably exhibited. In addition, tackiness is low and handling is excellent.

The adhesive polyurethane has a weight average molecular weight of 5.6 × 10 ⁴ or less, preferably about 3.0 × 10 ⁴ to about 5.5 × 10 ⁴ , more preferably about 3.7 × 10 ⁴ to It is about 5.5 × 10 ⁴ . When the weight average molecular weight is larger than 5.6 × 10 ⁴ , the initial adhesive force is too low and positioning of the pressure-sensitive adhesive film becomes difficult and the handling property tends to be inferior. Moreover, there exists a tendency for normal-state adhesive force not to be fully obtained. When the weight average molecular weight is within the above range, it has an initial adhesive force that makes it easy to handle, and a normal adhesive strength that is high enough to withstand practical use. The weight average molecular weight of the adhesive polyurethane is, for example, adjusted by adjusting the weight average molecular weight of the polyester diol, adjusting the weight average molecular weight of the prepolymer, adjusting the isocyanate group content% of the prepolymer, or by chain extension reaction with diamine. It can adjust suitably by methods, such as adjusting.

  Adhesive polyurethane is obtained by the reaction of a prepolymer and a diamine, but the adhesive polyurethane in the present invention is obtained from a raw material replacing the prepolymer or diamine, and has the same chemical structure as the adhesive polyurethane obtained by the above reaction. What has is also included.

  The reaction between the prepolymer and the diamine can be performed, for example, by mixing the prepolymer and the diamine in an organic solvent under a nitrogen atmosphere. In such a reaction, the weight average molecular weight can be appropriately adjusted by adding a polymerization terminator. As the polymerization terminator, alkyl monoamines such as di-n-butylamine, mono-n-butylamine and 2-ethylhexylamine, hydroxyl monoamines such as diethanolamine and monoethanolamine, and the like can be used.

  The adhesive polyurethane preferably does not contain an aromatic hydrocarbon group such as a benzene ring in the structure. When an aromatic hydrocarbon group is included, workability tends to be reduced due to an increase in tack and initial adhesion. Moreover, such an adhesive polyurethane tends to yellow, and when the film substrate is transparent, the appearance may be deteriorated.

  The adhesive layer can be obtained, for example, by preparing a solution containing 40 to 10% by mass of adhesive polyurethane, applying the solution onto a support such as a silicon liner, and drying. Examples of the solvent for the solution include methyl ethyl ketone, acetone, methyl isobutyl ketone, ethyl acetate, butyl acetate, toluene, xylene, ethanol, isopropanol, n-butanol, and the like. Of these, methyl ethyl ketone and ethyl acetate are preferred. The viscosity of the prepared solution is preferably about 100 to about 5,000 mPa · s. By setting it as such a solution, application | coating to a film base material or a support body becomes easy. The pressure-sensitive adhesive layer according to this embodiment is obtained by laminating the pressure-sensitive adhesive layer formed on the support in this manner on the film substrate and removing the support as necessary.

  Moreover, an adhesive layer can also be laminated | stacked directly on a film base material by apply | coating to a film base material and drying the solution containing 40-10 mass% adhesive polyurethane.

  The thickness of the adhesive layer is not particularly limited, but is preferably about 5 to about 50 μm, more preferably about 10 to about 30 μm. When the thickness is within the above range, there is an effect that moderate initial adhesiveness, cohesive force and finally sufficient normal adhesive force are more remarkably exhibited.

(Film substrate)
Since it is preferable that the pressure-sensitive adhesive film according to this embodiment can be used for modification and protection of an adherend having a three-dimensional (three-dimensional) shape, the film base material preferably has flexibility and stretchability. .

  As a film base material, since it is excellent in a softness | flexibility, a resin film base material is preferable. Examples of the resin used for the film substrate include polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN); vinyl chloride resin; polyvinylidene fluoride resin; polycarbonate resin; Polyurethane resin; poly (meth) acrylate resin such as polymethyl methacrylate; polyolefin resin such as polyethylene and polypropylene; and the like.

  A plasticizer and other commonly used additives may be added to the film substrate.

  In addition, depending on the application, the film substrate may be added with inorganic particles such as silica, added with a function-imparting substance such as an ultraviolet absorber, colored with a colorant, or imparts printability to the surface. Therefore, a white pigment can be added. Moreover, you may print on the surface on the opposite side to the surface where the adhesive film of a film base material is laminated | stacked.

  In the pressure-sensitive adhesive film according to the present embodiment, there is almost no trace of peeling off at the time of peeling regardless of the level of glossiness of the surface of the film substrate. Therefore, film base materials having various glossinesses can be used. The glossiness can be expressed by a 60 ° gloss value, and the range is not limited. The 60 ° gloss value can be, for example, about 40 or more, about 60 or more, about 70 or more, or about 90 or more.

  Although the thickness of a film base material is not specifically limited, Preferably it is about 5 to about 300 micrometers, More preferably, it is about 10 to about 100 micrometers.

(Measurement method of weight average molecular weight)
The weight average molecular weight (Mw) can be measured by gel permeation chromatography (hereinafter abbreviated as GPC). The measurement conditions are as follows.
Experimental equipment: Agilent Technologies / 1200 Series
Column: Plgel MIXED-Bx2 (300 mm, OD 7.5 mm, ID 5 mm, manufactured by Agilent Technologies)
Detector: RI (refractive index) Wyatt / Optilab rEX
Solvent: Tetrahydrofuran flow rate: 1.0 ml / min Sample concentration: 0.1%
Standard: Polystyrene

Example 1
[Preparation of adhesive polyurethane 1]
In a flask equipped with a stirrer, a thermometer and a nitrogen introduction tube, 500 parts by mass of P-4010 (number average molecular weight 4000), poly (3-methyl-1,5-pentanediol adipate) glycol manufactured by Kuraray, isophorone diisocyanate 60 A mass part was charged and reacted at 100 ° C. for 6 hours under a nitrogen stream, and then 400 parts by mass of ethyl acetate was added to obtain a uniform solution of a urethane prepolymer. Next, 1000 parts by mass of the urethane prepolymer solution is added to a mixture consisting of 19 parts by mass of isophoronediamine, 5 parts by mass of dibutylamine, 600 parts by mass of ethyl acetate and 500 parts by mass of isopropyl alcohol, and reacted at 50 ° C. for 6 hours. It was confirmed by the infrared absorption spectrum that NCO characteristic absorption was burned out, and the reaction was completed. According to the above measurement method, the weight average molecular weight of the adhesive polyurethane 1 was measured. The measurement results are shown in Table 1. Table 1 shows the result of composition analysis of the adhesive polyurethane 1. AD represents an alkyl diol residue, AA represents an adipic acid residue, IP represents an isophorone skeleton, and AD / AA / IP represents a ratio (mass ratio) of each structure in the adhesive polyurethane. The following equipment was used for composition analysis. The alkyldiol residue indicates a partial structure obtained by removing a hydrogen atom from two hydroxyl groups of the alkyldiol, and the adipic acid residue indicates a partial structure obtained by removing an OH group from two carboxyl groups of adipic acid.
FT-IR: Thermo Electron / Nicolet Nexus670
GC / MS: (GC) manufactured by Agilent Technologies / 6890 Series, (MSD) manufactured by Agilent Technologies / 5973
C ¹³ -NMR :( heavy solvent) deuterated chloroform / deuterated methanol (deuterochloroform 85 volume%, heavy methanol 15 vol%, chromium (III) acetylacetonate trace containing (Note that the trace, for example 0.1 vol% JEM-ECA600 NMR (150 MHz, lH decoupling without NOE), manufactured by JEOL Ltd.

[Creation of adhesive film 1]
Adhesive polyurethane 1 was appropriately prepared with ethyl acetate to obtain a solution having a solid content of 30%. At this time, the viscosity was 600 mPa · s. This solution was applied onto a silicon liner with a bar coater so as to have a dry thickness of about 25 μm, and dried to obtain an adhesive layer. This pressure-sensitive adhesive layer was bonded to a polyurethane (PUR) film (manufactured by Sumitomo 3M, trade name: 720LF, thickness: 40 μm) as a film base material, and the silicon liner was peeled off to obtain a pressure-sensitive adhesive film 1.

(Examples 2 and 3)
Adhesive polyurethane 2 and adhesive polyurethane 3 were prepared in the same manner as in Example 1 except that the weight average molecular weight and composition ratio (AD / AA / IP) shown in Table 1 were used. An adhesive film 2 and an adhesive film 3 were prepared in the same manner as in Example 1 except that the adhesive polyurethane 1 was changed to an adhesive polyurethane 2 and an adhesive polyurethane 3, respectively.

(Examples 4 and 5)
Kuraray P-4010 was changed to poly (2-methyl-1,3-propanediol adipate) glycol having a number average molecular weight of about 2,000, and the weight average molecular weight and composition ratio (AD / AA / IP adhesive polyurethane 4 and adhesive polyurethane 5 were prepared in the same manner as in Example 1 except that IP). An adhesive film 4 and an adhesive film 5 were prepared in the same manner as in Example 1 except that the adhesive polyurethane 1 was changed to an adhesive polyurethane 4 and an adhesive polyurethane 5, respectively.

(Comparative Examples 1 and 2)
Adhesive polyurethane 6 and adhesive polyurethane 7 were prepared in the same manner as in Example 1 except that the weight average molecular weight and composition ratio (AD / AA / IP) shown in Table 1 were used. An adhesive film 6 and an adhesive film 7 were prepared in the same manner as in Example 1 except that the adhesive polyurethane 1 was changed to an adhesive polyurethane 6 and an adhesive polyurethane 7, respectively.

(Comparative Example 3)
Adhesive polyurethane 8 was prepared in the same manner as in Example 1 except that isophorone diisocyanate was changed to 4,4′-methylenediphenyl diisocyanate. MDI represents a 4,4′-methylenediphenyl diisocyanate residue. The 4,4′-methylenediphenyl diisocyanate residue indicates a partial structure derived from 4,4′-methylenediphenyl diisocyanate. An adhesive film 8 was prepared in the same manner as in Example 1 except that the adhesive polyurethane 1 was changed to the adhesive polyurethane 8.

(Comparative Example 4)
An adhesive polyurethane 9 was prepared in the same manner as in Example 1 except that isophorone diisocyanate was changed to 4,4′-methylenediphenyl diisocyanate so that the composition ratio (AD / AA / MDI) shown in Table 1 was obtained. did. An adhesive film 9 was prepared in the same manner as in Example 1 except that the adhesive polyurethane 1 was changed to the adhesive polyurethane 9.

(Comparative Example 5)
SK Dyne 1310 (acrylic adhesive) manufactured by Soken Chemical Co., Ltd. and isocyanate L45 manufactured by Nippon Polyurethane Co., Ltd. were mixed at a mass ratio of 100/1 and diluted with ethyl acetate to prepare a solution having a solid content of 30%. This solution was applied onto a silicon liner with a bar coater so as to have a dry thickness of about 25 μm, and dried to obtain an adhesive layer. This pressure-sensitive adhesive layer was bonded to a polyurethane (PUR) film (thickness 40 μm), and the silicone liner was peeled off to obtain a pressure-sensitive adhesive film 10.

(Measurement of adhesive strength)
About each adhesive film obtained in Examples 1-5 and Comparative Examples 1-5, the adhesive force was measured with the following method.
[Measurement method of adhesive strength]
The pressure-sensitive adhesive film was cut into a width of 25 mm and a length of 200 mm, and pressed under a standard condition (temperature 21 ° C., humidity 65%) by reciprocating a 2 kg roller twice. This was peeled off with Tensilon manufactured by A & D at a peeling angle of 180 degrees and a peeling speed of 300 mm / min, and the adhesive strength was measured. Table 1 shows a measured value (0h) in less than 1 minute, a measured value (1h) in 1 hour, and a measured value (48h) in 48 hours from the time of pressing to peeling.

(Example 6)
An adhesive film was prepared using the adhesive polyurethane 1 of Example 1 and each substrate shown in Table 2 as a film substrate.

(Example 7)
An adhesive film was prepared using the adhesive polyurethane 3 of Example 3 and each substrate shown in Table 2 as a film substrate.

(Comparative Example 6)
Using the mixture of Comparative Example 5, an adhesive film was prepared using each substrate shown in Table 2 as a film substrate.

(Comparative Example 7)
An adhesive film was prepared by using the adhesive composition 8 of Comparative Example 3 and using each substrate shown in Table 2 as a film substrate.

(Appearance of the peeling mark)
About each adhesive film obtained in Examples 6-7 and Comparative Examples 6-7, the appearance evaluation of the peeling mark was performed by the following method.
[Appearance evaluation method of peeled off marks]
The operation of attaching the adhesive film to the melamine-coated plate with a squeegee and immediately peeling it off was repeated three times, and the presence or absence of a peeling mark was confirmed visually. Evaluation was performed as follows.
A: Lines are not visible.
B: Streaks appear faint.
C: Lines are clearly visible.

The film base material used is shown below. Further, the glossiness (gloss measurement) of each film substrate was measured using a Murakami color lighting scale 60 °. The results are shown in Table 2.
Base material 1: highly transparent polyester film, T60 (manufactured by Toray Industries, Inc.), thickness 25 μm.
Base material 2: Highly transparent polyester film, T60 (manufactured by Toray Industries, Inc.), thickness 50 μm.
Substrate 3: Matte polyester film (PET), U4 (manufactured by Teijin DuPont), thickness 50 μm.
Substrate 4: Matte-like polyurethane film (PUR), thickness 10 μm.
Base material 5: White polyurethane film (PUR), thickness 33 μm.
Base material 6: Metallic appearance polyurethane film (PUR), thickness 40 μm.
Substrate 7: Transparent polyvinyl chloride film (PVC), thickness 50 μm.
Base material 8: White polyvinyl chloride film (PVC), thickness 50 μm.
Base material 9: white polyvinyl chloride film (PVC), thickness 95 μm.
Substrate 10: Transparent polyvinylidene fluoride film (PCDF), DX (manufactured by Denki Kagaku Kogyo Co., Ltd.), thickness 50 μm.

  DESCRIPTION OF SYMBOLS 1 ... Adhesive film, 2 ... Film base material, 3 ... Adhesive layer.

Claims (3)

An adhesive film comprising an adhesive layer on a film substrate,
The pressure-sensitive adhesive layer has a weight average molecular weight of 5.6 × obtained by chain-extending a prepolymer obtained by reacting a diol obtained by condensing an alkanediol having 4 to 8 carbon atoms and adipic acid with isophorone diisocyanate. An adhesive film which is a layer containing 10 ⁴ or less adhesive polyurethane.   The pressure-sensitive adhesive film according to claim 1, wherein the alkanediol having 4 to 8 carbon atoms is 3-methyl-1,5-pentanediol or 2-methyl-1,3-propanediol.   The pressure-sensitive adhesive film according to claim 1, wherein the film base material is a resin film base material.

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