JP2003221570A - Polyurethane adhesive composition and pressure- sensitive adhesive sheet using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a repeelable pressure-sensitive polyurethane adhesive composition having excellent adhesion, transparency and weather resistance, hardly leaving the adhesive, and capable of being repeatedly used, and to provide a pressure-sensitive adhesive sheet obtained by coating the adhesive composition on a base material, and having excellent characteristics. <P>SOLUTION: This adhesive composition uses (A) a polyol component comprising the diol component consisting essentially of a polyether-diol and/or a polyester diol having an aromatic ring and a polyoxyalkylene group in the molecule, and a polyether triol in a prescribed ratio, and (B) a polyisocyanate component comprising an aliphatic or alicyclic polyisocyanate, or a prepolymer obtained by using the polyisocyanate and having an isocyanate group at the terminal. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polyurethane pressure-sensitive adhesive composition which is preferably used for pressure-sensitive adhesive seals and labels, and a pressure-sensitive adhesive sheet obtained by coating the same.

[0002]

2. Description of the Related Art Conventionally, as an adhesive used for a seal, a label, etc., an acrylic resin type, a rubber type resin, a vinyl acetate type resin or the like is mainly used. The pressure-sensitive adhesive sheet coated with these pressure-sensitive adhesives has excellent adhesive strength, but has poor removability, and may cause adhesive residue when peeled from the adherend after being attached to the adherend. . In addition, when the surface of the pressure-sensitive adhesive layer is soiled with dust or the like, it is difficult to remove the soil even after washing with water, which reduces the adhesive strength and makes it difficult to re-bond them.

Since urethane resin has excellent physical properties such as toughness and flexibility, it is used in many fields and is also used as an adhesive (Japanese Patent Publication No. 53-31192 / 1987 and Japanese Patent Laid-Open No. 62-106978). (See No.

However, when urethane resin is used as an adhesive, its performance is greatly affected by the raw material used. That is, polyester polyols and polyether polyols are known as the polyol component used in the two-component urethane pressure-sensitive adhesive.
When a commonly used polyester polyol having a high glass transition point is used, although the cohesive force of the pressure-sensitive adhesive increases, the hardness of the pressure-sensitive adhesive layer itself also increases and the adhesion to the adherend decreases, resulting in good It becomes difficult to develop adhesive strength,
There has been a problem that the liquid viscosity of the pressure-sensitive adhesive composition is increased and the workability is lowered.

On the other hand, when a polyether polyol is used as the polyol component, the glass transition point of the pressure-sensitive adhesive is lowered, the flexibility is improved and the tackiness is improved, but the cohesive force of the pressure-sensitive adhesive is reduced and the adhesive There was a problem that it was easy to remain. Further, when the strength of the pressure-sensitive adhesive layer is increased by a method such as increasing the crosslink density, the adhesive residue can be prevented but the adhesive force is reduced.

Therefore, in the present urethane resin-based pressure-sensitive adhesives, polyester polyols having a low glass transition point are used as the polyol component in order to prevent adhesive residue and enhance adhesive strength, or complement each other's drawbacks. In order to do so, a plurality of types of polyols such as general-purpose polyester polyol and polyether polyol are blended and used. Further, in some cases, these polyols are reacted with less than the reaction equivalent of diisocyanate to form a polyol-based prepolymer having a hydroxyl group at the terminal in advance, and this is reacted with a polyfunctional isocyanate to obtain an adhesive.

[0007]

However, in the above-mentioned pressure-sensitive adhesive, the polyester polyol added to improve the tackiness is liable to cause turbidity because it is originally easily crystallized, and is compatible with the polyether polyol. However, there is a problem that it is difficult to obtain a highly transparent pressure-sensitive adhesive because it is low.

In view of the above, the present invention provides a releasable urethane pressure-sensitive adhesive composition which is excellent in tackiness, transparency and weather resistance, has no adhesive residue, and can be repeatedly used, and is applied to a sheet material. The purpose is to obtain a pressure-sensitive adhesive sheet having excellent properties.

[0009]

In order to achieve the above object, the polyurethane adhesive composition according to the present invention comprises a polyether diol having an aromatic ring and a polyoxyalkylene group in the molecule (hereinafter, referred to as "aromatic poly (Hereinafter referred to as "ether diol") as a main component, and a polyol component (A) containing a polyether triol,
Alternatively, a polyol-based prepolymer (A1) having a hydroxyl group at the terminal, which is obtained by mixing the polyol component (A) with an aliphatic or alicyclic diisocyanate in an amount less than the reaction equivalent and reacting the mixture.
And an aliphatic or alicyclic polyisocyanate (B) or a prepolymer (B1) having an isocyanate group at the terminal, which is obtained by using the polyisocyanate (B).

According to the above-mentioned constitution, since the diol component containing the aromatic polyether diol as the main component and the polyether triol are used as the polyol component, the obtained pressure-sensitive adhesive is excellent in flexibility, and further the polyether is used. Since the diol has an aromatic ring in the molecule, the cohesive force of the pressure-sensitive adhesive is increased, the adhesiveness is improved, and the adhesive residue can be suppressed.

Further, since an aliphatic or alicyclic isocyanate component is used as the isocyanate component, the adhesive is less colored and discolored with time, and since the polyol component is a polyether type, it is excellent in transparency. An adhesive can be obtained.

On the other hand, since polyester diol has a structurally high cohesive energy, it is possible to enhance the cohesive force of the adhesive as compared with the aromatic polyether diol. However, as described above, when the polyester polyol is used, the hardness of the pressure-sensitive adhesive layer itself becomes high and the adhesion to the adherend is lowered, and it becomes difficult to express good adhesive strength, and the polyether polyol is used. However, there is a problem that it is difficult to obtain a highly transparent pressure-sensitive adhesive because of low compatibility.

Therefore, as a result of various investigations by the present inventor, when a specific polyester diol is used as a diol component, flexibility can be imparted to the pressure-sensitive adhesive while maintaining high cohesive force, resulting in more tackiness. It has been found that an adhesive having excellent properties can be obtained.

That is, in the present invention, as a polyurethane adhesive composition, a polyester diol having an aromatic ring and a polyoxyalkylene group in the molecule (hereinafter, referred to as
"Aromatic polyester diol") as a main component, and a polyol component (A) containing a polyether triol, or an aliphatic or alicyclic group having a reaction equivalent to the polyol component (A). A polyol-based prepolymer (A1) having a hydroxyl group at the terminal obtained by mixing and reacting a diisocyanate with an aliphatic or alicyclic polyisocyanate (B), or an isocyanate at the terminal using the polyisocyanate (B) It is possible to adopt a constitution comprising a prepolymer (B1) having a group.

According to the above constitution, since the aromatic polyester diol is used as the diol component in the polyol, the adhesive has a high cohesive force and does not cause adhesive residue, and further has a polyoxyalkylene group in the molecule. Since it has, it becomes possible to obtain an adhesive with excellent flexibility. The obtained pressure-sensitive adhesive exhibits extremely good pressure-sensitive adhesiveness due to its high cohesive strength and excellent flexibility.

Further, since the aromatic polyester diol has a polyoxyalkylene group in the molecule, it has good compatibility with the polyether triol and a pressure sensitive adhesive having excellent transparency can be obtained.

The above-mentioned aromatic polyether diol and aromatic polyester diol can be used in combination. That is, as the diol component, one having a mixture of a polyether diol having an aromatic ring in the molecule and a polyester diol having an aromatic ring and a polyoxyalkylene group in the molecule as a main component can be used.

As the aromatic polyether diol in the molecule used in the present invention, bisphenols such as bisphenol A and bisphenol AD, and bisphenols such as catechol, resorcin, and hydroquinone are used as an initiator. Examples thereof include those obtained by addition-polymerizing alkylene oxides such as ethylene oxide, propylene oxide and butylene oxide.

As the diol component, it is preferable to use the above-mentioned aromatic polyether diol alone, but the viscosity tends to increase by introducing an aromatic ring into the molecular skeleton. In order to secure the property or to adjust the cohesive force of the pressure-sensitive adhesive, an aliphatic polyether diol having ethylene glycol or propylene glycol as an initiator may be used in combination. In this case, 50% by weight or more of the whole diol is contained so that the aromatic polyether diol is the main component of the diol. This makes it possible to improve the cohesive force of the pressure-sensitive adhesive.

The number average molecular weight (hereinafter referred to as Mn) of the polyether diol is preferably 300 to 1500. More preferably, it is 350 to 1000. When Mn is less than 300, the pressure-sensitive adhesive layer may be too hard, and when it is more than 1500, the aromatic ring content may be decreased and the cohesive force (adhesive force) may be decreased.

Examples of commercially available products of the above aromatic polyether diols include ADEKA polyether BPX-55 (Mn.
= 790, OHV = 135-150), the same BPX-33
(Mn = 580, OHV = 185-205), same BPX
-11 (Mn = 360, OHV = 300 to 320) and the like can be mentioned (these are all manufactured by Asahi Denka Kogyo Co., Ltd., OHV = hydroxyl value: mgKOH / g).

Examples of the aromatic polyester diol used in the present invention include aromatic dibasic acids such as phthalic acid, isophthalic acid, terephthalic acid, 2,6-dinaphthalenedicarboxylic acid and paraphenylenedicarboxylic acid as acid components. It is obtained by using it and reacting it with polyoxyalkylene glycol as a dihydric alcohol. It is also possible to use the polyether diol having an aromatic ring in the molecule as the dihydric alcohol.

As the diol component, it is preferable to use the above-mentioned aromatic polyester diol alone from the viewpoint of improving cohesive force, but since the viscosity tends to increase by introducing an aromatic ring into the molecular skeleton, the liquid An aliphatic polyester diol or the like may be used in combination for the purpose of adjusting the viscosity to ensure workability or for adjusting the cohesive force. In this case, 50% by weight or more of the entire diol is contained so that the aromatic polyester diol is the main component of the diol. This makes it possible to improve the cohesive force of the pressure-sensitive adhesive.

The molecular weight of the polyester diol is preferably 700 to 3000 in terms of Mn. More preferably 1000
~ 2500. If Mn is less than 700, the pressure-sensitive adhesive layer may be too hard, and if it is more than 3,000, the viscosity may be high and handling may be difficult, resulting in lack of practicality. Examples of commercially available products of the above aromatic polyester diol include Polylite ODX-2360 (Mn =
2000, OHV = 53 to 59, manufactured by Dainippon Ink and Chemicals, Inc.). When the aromatic polyether diol and the aromatic polyester diol are used in combination, the molecular weights of the aromatic polyether diol and the aromatic polyester diol are preferably those within the above-mentioned ranges.

As the polyether triol, for example, a polyoxyalkylene triol obtained by addition-polymerizing alkylene oxide using a triol such as glycerin, trimethylolpropane and triethanolamine as an initiator can be used. The molecular weight of the polyether triol is preferably 1500 to 7000 in terms of Mn. More preferably, it is 2000 to 6000. Mn is 1500
When it is lower, the crosslink density is high and the tackiness is low. On the contrary, when it is higher than 7,000, the crosslink density is low and the tackiness is high, but there is a risk of adhesive residue. Examples of commercially available products of the above polyether triol include Exenol 5030 (Mn = 5100, OHV =
33, manufactured by Asahi Glass Industry Co., Ltd.) and the like.

The mixing ratio of the diol component and the triol is
The equivalent ratio of the hydroxyl groups possessed by each is preferably 10: 1 to 1: 1 and more preferably 5: 1 to 2: 1. When the triol component is reduced to less than 10: 1, the crosslink density is reduced, the tackiness is increased, and the adhesive residue tends to remain. On the other hand, when the triol component is increased and becomes larger than 1: 1, the crosslink density is increased and the tackiness is decreased.

In addition to the above-mentioned diols and triols, polyester polyols such as condensation type polyester polyols, lactone type polyester polyols, polycarbonate diols, rosin acid ester type diols, and polyether polyols may be used as long as the effects of the present invention are not impaired. A polyol obtained by addition-polymerizing alkylene oxide with pentaerythritol, ethylenediamine, sorbitol or the like as an initiator may be added.

The polyol-based prepolymer (A1) is obtained by reacting the polyol component (A) with a small amount of an aliphatic or alicyclic diisocyanate, that is, the NCO / OH equivalent ratio is less than 1. Further, it is a prepolymer having a hydroxyl group at the terminal.

The aliphatic diisocyanate used in the present invention includes tetramethylene diisocyanate,
Examples include pentamethylene diisocyanate, hexamethylene diisocyanate (HDI), trimethylhexane diisocyanate, and the like. Further, examples of the alicyclic diisocyanate include isophorone diisocyanate, hydrogenated xylene diisocyanate, hydrogenated methylenebisphenylene diisocyanate and the like. These aliphatic and alicyclic diisocyanates have the effect of improving the weather resistance of the pressure-sensitive adhesive.

As the polyisocyanate component, an aliphatic or alicyclic polyisocyanate (B) may be used, or an excess of an aliphatic or alicyclic polyisocyanate (B) may be used.
In addition, a prepolymer (B1) having an isocyanate group at the terminal, which is obtained by reacting with a polyester polyol or a polyether polyol, may be used.

As the polyester polyol or polyether polyol used as the raw material of the prepolymer (B1), those used in the synthesis of ordinary polyurethane prepolymers can be used.

That is, as the polyester polyol used as a raw material of the prepolymer (B1), phthalic acid, isophthalic acid, terephthalic acid, adipic acid, azelaic acid, sebacic acid, trimellitic acid, etc.
Ethylene glycol, propylene glycol, diethylene glycol, butylene glycol, 1,6-hexane glycol, 3-methyl-1,5-pentanediol, 3,3'-dimethylolheptane, polyoxyethylene glycol, polyoxypropylene glycol, 1, Examples thereof include those obtained by reacting a glycol component such as 4-butanediol, neopentyl glycol and butylethylpentanediol, or a polyol component such as glycerin, trimethylolpropane and pentaerythritol.

As the polyether polyol used as a raw material of the prepolymer (B1), a polyol such as propylene glycol, ethylene glycol, glycerin or trimethylolpropane is used as an initiator, and ethylene oxide, propylene oxide, butylene oxide or the like is used. The thing which added-polymerized the alkylene oxide can be mentioned. As these polyols, those having Mn of 500 to 10,000 are used, preferably 1,000 to 3,000.

The prepolymer (B1) has an average number of isocyanate groups (hereinafter, referred to as "average number of functional groups") contained in one molecule in order to obtain an adhesive having adhesiveness and good removability. It is preferably 2.2 or more and less than 3.0. Here, as for the average number of functional groups, the number average molecular weight (Mn) of the synthesized polyisocyanate (B) is measured by GPC analysis, and from the measurement result of the isocyanate group content rate (%) (hereinafter, NCO%), It can be calculated by the following formula. Average number of functional groups = [NCO (%)
× Mn] / [42 × 100]

When the average number of functional groups is less than 2.2, the cross-linking density of the resulting pressure-sensitive adhesive becomes small, the tackiness becomes too high, and the adhesive is liable to be left behind during re-peeling. On the contrary, 3.
If it is 0 or more, the crosslink density becomes high, and the adhesiveness may decrease. In order to obtain a polyisocyanate prepolymer having an average number of functional groups of 2.2 or more and less than 3.0, a trifunctional polyisocyanate obtained by reacting an excess diisocyanate with a low molecular weight triol (for example, Coronate HL manufactured by Nippon Polyurethane Industry Co., Ltd.) is used. ) Or a trimer of diisocyanate having an isocyanurate structure (for example, Coronate HX manufactured by Nippon Polyurethane Industry Co., Ltd.) is mixed with the diisocyanate.

Further, it can also be obtained by appropriately mixing a bifunctional prepolymer having an isocyanate group at the terminal and a trifunctional prepolymer. It may be a reaction mixture obtained by reacting an excess diisocyanate or a prepolymer having two isocyanate groups at the terminal with a triol, or an excess triisocyanate with a diol. In the present invention, it is desirable to obtain a desired number of functional groups by reacting a commercially available product with a polyisocyanate having a functional number of more than 2 and a polyol.

Examples of the low molecular weight isocyanate having a functional group of 3.0 or more include, for example, H of trimethylolpropane.
DI adduct and HDI trimer alone can be mentioned. Examples of commercially available products include HDI adduct of Coronate HL (manufactured by Nippon Polyurethane Industry Co., Ltd.) and HDI trimer of Coronate HX (manufactured by Nippon Polyurethane Industry Co., Ltd.). The body etc. are mentioned.

The polyol component (A) or the polyol-based prepolymer (A1) contains a nitrogen-containing compound such as triethylamine or triethylenediamine or dibutyltin dilaurate (DBTDL) as a catalyst for promoting urethanization.
Organic acid tin compounds such as dioctyl tin dilaurate (DOTDL) and other catalysts usually used for the reaction between isocyanate groups and hydroxyl groups can be added.

As the additive of the pressure-sensitive adhesive composition, an antioxidant for polyurethane (for example, phenolic Irganox 1010 (manufactured by Ciba Specialty Chemicals), Adeka Stab AO-60, Adeka Stub AO-8)
0 (all manufactured by Asahi Denka Kogyo Co., Ltd.), phosphite type Irgafos-168 (manufactured by Ciba Specialty Chemicals), ADEKA STAB 260 (manufactured by Asahi Denka Kogyo Co., Ltd.), an ultraviolet absorber, a light stabilizer (eg, , Syasorb UV-5411 (manufactured by Scitech Industries), Chinubin 765 (manufactured by Ciba Specialty Chemicals), ADEKA STAB LA-62 (manufactured by Asahi Denka Kogyo Co., Ltd.), Chinubin P (manufactured by Ciba Specialty Chemicals), etc. Is a hydrolysis inhibitor (for example, Starbuxol I (Sumitomo Bayer Urethane Co., Ltd.),
DIPC (N, N-bis (2,6-diisopropylphenyl) carbodiimide, manufactured by Nippon Carbide Industry Co., Ltd.)
Can also be added.

If it is necessary to impart greater tackiness to the pressure-sensitive adhesive of the present invention, a colorless or light-colored tackifier such as xylene-formaldehyde resin, terpene resin, rosin resin, petroleum resin can be added. .

During the synthesis of the polyol component (A) and urethane prepolymer (A1) of the present invention, it is used for dissolving a known urethane resin in order to obtain a good coating viscosity and to adjust the reaction rate of the prepolymer. The solvent used can be used. Examples of the solvent used for such purpose include toluene, xylene, acetone, methyl ethyl ketone, ethyl acetate, tetrahydrofuran and the like.

A pressure-sensitive adhesive sheet can be obtained by applying the above-mentioned polyurethane pressure-sensitive adhesive composition to a sheet material.
As the sheet material, a base material such as paper, synthetic paper, a plastic film or a plastic sheet can be used as it is, and a metal layer is formed on the base material, or a print layer or an overcoat layer for print protection is formed. You may use what was done.

There is no specific method for coating the polyurethane adhesive composition, but after mixing the polyol component (A) and the polyisocyanate component (B) in a predetermined ratio,
For example, it can be applied by a blade coater, a knife coater, a kiss coater, a gravure coater, or the like, or by casting. After coating, it is desirable to heat to accelerate curing, but the heating method is hot air heating,
Far infrared heating method can be used. There is no specific determination of the form or amount of the adhesive such as thick film or thin film to be applied to the sheet material, and it can be set arbitrarily.

The pressure-sensitive adhesive sheet obtained as described above is
The adhesive layer is pale and transparent, and has excellent adhesiveness and weather resistance. Further, it can be peeled off without leaving an adhesive residue, and when it becomes dirty, it can be reused by washing with water, and the adhesiveness can be reused. Therefore, it can be suitably used for adhesive seals, labels and the like.

For example, if a sheet material having a metal foil laminated on a base material or a metal layer having a metal deposited thereon is used as a sheet material for applying an adhesive, an adhesive sheet that reflects light and heat is obtained. If this reflective sheet is attached to the window of a vehicle such as a house or an automobile, it can be attached to the window only when necessary to prevent the occurrence of dew condensation, cut strong sunlight, and eliminate unnecessary It can be easily peeled off. Moreover, since the pressure-sensitive adhesive layer of the reflective sheet has excellent weather resistance, the pressure-sensitive adhesive layer is not significantly deteriorated and can be used for a long period of time.

Furthermore, a light-reducing sheet that cuts off a part of light can be obtained by using a sheet material in which a UV absorber or a coloring agent is added to a light-transmitting substrate instead of the metal layer. It will be possible. In this case, since the pressure-sensitive adhesive has excellent transparency, it has an excellent effect of not impairing the visibility of the outside scenery.

The excellent transparency of the above-mentioned pressure-sensitive adhesive exhibits excellent effects not only in the light-reducing sheet but also in other applications.
For example, in a translucent label in which a printing layer is provided on a translucent substrate, the transparency of the pressure-sensitive adhesive layer is low in the conventional product, and the visibility of the label display due to the color change of the pressure-sensitive adhesive layer over time. However, since the pressure-sensitive adhesive sheet according to the present invention has a high transparency of the pressure-sensitive adhesive layer and little discoloration with time, it is possible to maintain good label visibility.

Besides, by utilizing the good releasability of the pressure-sensitive adhesive layer, not only the printing layer is formed on the surface side of the sheet material of the pressure-sensitive adhesive sheet, but also the pressure-sensitive adhesive layer side, that is, the pressure-sensitive adhesive layer and the sheet. If a printing layer is also provided between the materials, a double-sided printing pressure-sensitive adhesive sheet can be obtained in which the content of the printing layer on the pressure-sensitive adhesive layer side can be seen. Also in this case, due to the excellent transparency of the pressure-sensitive adhesive layer, the contents of the printed layer can be sufficiently visually recognized through the pressure-sensitive adhesive layer.

The adhesive strength of the pressure-sensitive adhesive can be controlled relatively easily by adjusting the compounding ratio of the isocyanate component (B) and the polyol component (A) in the composition. The compounding ratio is the equivalent ratio R (R = N) of all the isocyanate groups in the polyisocyanate (B) or the prepolymer (B1) and all the hydroxyl groups in the polyol component (A) or (A1).
It is a value obtained by the number of CO equivalents / the number of OH equivalents. The larger the R value, the smaller the adhesive strength.

The equivalent ratio R preferred in the present invention is 0.5 to
1.1, and more preferably 0.6 to 0.95. If the equivalent ratio R exceeds 1.1, the resin may gel during synthesis of the pressure-sensitive adhesive and coating may not be possible. If the equivalent ratio R is less than 0.5, the resin may not have a high molecular weight and the function as a pressure-sensitive adhesive may not be achieved. It will not be exhibited. It is also possible to prepare a pressure-sensitive adhesive having different adhesive strengths by utilizing such characteristics of the pressure-sensitive adhesive and provide a laminated pressure-sensitive adhesive sheet using the plurality of pressure-sensitive adhesive compositions.

That is, as the laminated pressure-sensitive adhesive sheet,
A plurality of sheet materials are arranged in layers, an adhesive layer made of a polyurethane adhesive composition is interposed between the sheet materials, and the adhesive layer cannot be peeled off to one of the sheet materials on both sides thereof. Is applied to the sheet material on the other side so that it can be peeled off, and an adhesive layer for adhering to the adherend is applied to the back surface of the sheet material on the lower layer side. , The adhesive strength is set to be lower than that of the adhesive layer.

The non-removable or releasable coating of the pressure-sensitive adhesive layer means that among the sheet materials on both sides of the pressure-sensitive adhesive layer,
By making a sufficient difference in adhesive strength between the sheet material on one side and the sheet material on the other side, when the sheet material is pulled up, the adhesive layer always remains only on the sheet material on one side, It means that it can be peeled off without remaining on the side sheet material.
As a method of making a sufficient difference in adhesive strength, for example,
By appropriately roughening the surface of the sheet material on one side and smoothing the surface of the sheet material on the other side, the adhesive strength may be made different due to the difference in anchor effect. The adhesive strength may be weakened by forming a release agent layer or a print protection overcoat layer.

According to the above construction, the sheet material can be peeled off with the adhesive layer of the adhesive sheet adhered to the surface of the adherend. As the adhesive, if the lowermost sheet material is left adhered to the surface of the adherend, a commonly used non-peeling adhesive such as a strong adhesive type adhesive made of acrylic resin, etc. The agent may be used.

When the lowermost sheet material is also removable, the pressure-sensitive adhesive composition according to the present invention can be used as an adhesive. In this case, by adjusting the equivalent ratio R, it becomes possible to form an adhesive layer having good peelability and high adhesive strength. In addition,
The adhesive strength of the adhesive can be easily set to be smaller than that of the adhesive by changing the equivalence ratio R.

As the adhesive, it is also possible to use a non-peeling adhesive for a part of the sheet material and the polyurethane pressure-sensitive adhesive composition according to the present invention for the other parts.
In this case, the back surface side can be visually recognized without removing the lowermost layer (lower layer side) sheet material from the adherend.
Further, the number of the sheet materials may be two, that is, the pressure-sensitive adhesive layer may be only one layer, or the number of the sheet materials may be three or more. When the number of sheet materials is three or more, a plurality of pressure-sensitive adhesive layers are formed. However, by providing a difference in adhesive strength between the pressure-sensitive adhesive layers, it becomes possible to peel off only an arbitrary sheet material.

That is, in the present invention, three or more sheet materials are arranged in layers, and an adhesive layer made of the polyurethane adhesive composition of the present invention is interposed between each sheet material, and the adhesive layers are Of the sheet materials on both sides thereof, it is a non-removable coating on one sheet material, and is a laminated type adhesive sheet releasably attached to the other side sheet material, wherein the adhesive layer is The pressure-sensitive adhesive sheet is provided such that the lowest layer has the highest adhesive strength and the lower the layer, the lower the adhesive strength.

According to the above construction, for example, when the uppermost sheet material is peeled off, the sheet materials of the second and subsequent layers are integrally joined to each other due to the difference in the adhesive force of the adhesive layers. Hold the state.

In the conventional pressure-sensitive adhesive, in the punching property at the time of punching the pressure-sensitive adhesive label, if the pressure-sensitive adhesive layer is thickened in order to increase the adhesive force, stringing and adhesion of the pressure-sensitive adhesive occur during punching, which adversely affects productivity and quality. The adhesive strength may not be so high because of the adhesive residue at the time of peeling. Therefore, the adhesive layer with the maximum adhesive strength (the lowermost adhesive layer) and the minimum adhesive strength It was not possible to make the difference in adhesive strength with the one (the uppermost adhesive layer) very large. Therefore, if the uppermost layer is peeled off, the next layer is also peeled off.

On the other hand, in the pressure-sensitive adhesive composition according to the present invention, the pressure-sensitive adhesive having the maximum pressure-sensitive adhesive strength has a high pressure-sensitive adhesive strength even when applied thinly, has excellent punchability, and does not cause adhesive residue. It is possible to make a large difference in the adhesive force between the layer (the lowermost adhesive layer) and the layer having the minimum adhesive force (the uppermost adhesive layer).

Therefore, by changing the equivalent ratio R while using the same kind of pressure-sensitive adhesive without changing the pressure-sensitive adhesive type, only the layer to be peeled can be smoothly peeled off. Can be easily obtained. In the above structure, the adhesive layer may or may not be formed. Further, as the plurality of sheet materials, in addition to using separate sheet materials, one sheet material may be folded back and overlapped.

[0061]

EXAMPLES The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to these. [Preparation of polyol component and polyisocyanate-based prepolymer component] Using the raw materials shown in Tables 1 and 2, the polyol component (A) or the polyol-based prepolymer (A
1) and a polyisocyanate-based prepolymer component (B)
And were prepared. The synthesis method of each component is shown below.

[0062]

[Table 1]

[0063]

[Table 2]

<Synthesis Example 1> As shown in Table 1, as the polyol component (A), a diol component mainly containing a phthalic acid type aromatic polyester diol having a polyoxyalkylene group (trade name: ODX-2360). , Mn = 2
000, manufactured by Dainippon Ink and Co., Ltd.) and polyether triol (trade name: EXCENOL 5030, Mn = 5100, manufactured by Asahi Glass Urethane Co., Ltd.) using glycerin as an initiator, and both are dehydrated, and then diol. 1200 g and 670 g were weighed so that the equivalence ratio of the hydroxyl groups of the components and triol was 3: 1, and 120 g of ethyl acetate was added to the container and stirred.

Next, 5 g of Fomelets UL-28 (made by Activator Chemical Co., Ltd.) as a tin-based catalyst, 10 g of ADEKA STAB AO-60 (made by Asahi Denka Kogyo Co., Ltd.) as a stabilizer, and ADEKA STAB LA-62 (Asahi) were placed in a container. Denka Kogyo Co., Ltd.) 10 g and Syasorb UV-5411 (manufactured by Cytec Industries) were added and stirred to adjust the polyol component (A-a).

<Synthesis Example 2> A polyol was prepared in the same manner as in Synthesis Example 1 except that Exenol 3030 (Mn = 3000, manufactured by Asahi Glass Urethane Co., Ltd.) having a small number average molecular weight was used as the polyether triol instead of Exenol 5030. The ingredients were adjusted.

That is, ODX-2 which is a diol component
360 g and 1200 g and 400 g, respectively, were weighed so that the equivalence ratio of hydroxyl groups to triol was 3: 1, and 100 g of ethyl acetate was added to a container and stirred, and then,
A catalyst and a stabilizer were added in the same manner as in Synthesis Example 1 and stirred to prepare a polyol component (Ab).

<Synthesis Example 3> As a diol component, BPX-55 (Mn = 790, Asahi Denka Kogyo Co., Ltd.), which is an aromatic polyether diol having bisphenol A as an initiator, is used instead of ODX-2360 which is a polyester diol. A polyol component was prepared in the same manner as in Synthesis Example 2 except that (Production) was used.

That is, BPX-5 which is a diol component
5 and 1000 g and 850 g, respectively, so that the equivalence ratio of the hydroxyl groups of the triol exenol 3030 would be 3: 1, 120 g of ethyl acetate and 120 g of ethyl acetate were added to the container and stirred, and then the same as in Synthesis Example 1. A catalyst and a stabilizer were added and stirred to adjust the polyol component (A-c).

<Synthesis Example 4> In this example, as a diol component, ODX-2360 containing an aromatic polyester diol as a main component and BPX-33 (Mn = 580, Asahi Denka Co., Ltd.) which is an aromatic polyether diol. It is characterized by using together with (made by the company).

That is, ODX-2360 and BPX-3
3 and 974 g were weighed and 192 g, respectively, and 6 parts of the triol Exenol 5030 was added thereto so that the equivalent ratio of the hydroxyl groups of the diol component and the triol was 4: 1.
After weighing 95 g, a container was added together with 120 g of ethyl acetate and stirred, and then a catalyst and a stabilizer were added in the same manner as in Synthesis Example 1 and stirred to adjust the polyol component (Ad).

<Synthesis Example 5> In this example, instead of the polyol component (A), a polyol-based prepolymer (A
1) was prepared. That is, in a 2 L separable flask, the equivalence ratio of the hydroxyl value of the diol component and the triol was 5:
1000 g of ODX-2 dehydrated to 1
360 and 340 g of Exenol 5030 were charged, and dibutyltin dilaurate (0.28 g) and ethyl acetate (335 g) as a urethane-forming catalyst were added thereto, and the mixture was uniformly stirred in a nitrogen stream in a mantle heater with adjustable temperature. Mixed. 101 g of hexamethylene diisocyanate was added thereto, and the reaction was carried out at 80 to 90 ° C. for 3 hours while uniformly stirring in a nitrogen stream.

Next, as a tin-based catalyst, Fomelets UL-2
5 g of 8 and 1 part of ADEKA STAB AO-60 as a stabilizer
0 g, 10 g of ADEKA STAB LA-62 and 5 g of Sayasorb UV-5411 were added and dissolved. The viscosity of the obtained polyol-based prepolymer having a terminal hydroxyl group is 2
It was 5450 mpa · s at 5 ° C.

<Synthesis Example 6> As a comparative material of the polyol component (A), Exenol 2020 which is a polyether diol containing no aromatic ring so that the equivalent ratio of the hydroxyl values of diol and triol is 3: 1. (Mn = 200
120 g (manufactured by Asahi Glass Urethane Co., Ltd.) and 67 g of Exenol 5030 as a polyethertriol were weighed and added to a container together with 120 g of ethyl acetate and stirred. A catalyst and a stabilizer were added thereto in the same manner as in Synthesis Example 1 and stirred to adjust the polyol component (A-f).

<Synthesis Example 7> As a comparative material of the polyol component (A), a polyester diol having an aromatic ring but not containing a polyoxyalkylene group (trade name: Hyplex HX-2030, Mn = 2000, Toho Rika Co., Ltd.) (Manufactured by the company) was used as a diol component, and Exenol 5030 was used as a polyether triol to prepare a polyol component.

Specifically, 1200 g and 670 g of dehydrated Hyplex HX-2030 and Exenol 5030 were weighed so that the equivalence ratio of the hydroxyl value of the diol component to the triol was 3: 1, and ethyl acetate 1
20 g was added to a container and stirred. A catalyst and a stabilizer were added thereto in the same manner as in Synthesis Example 1 and stirred to adjust the polyol component (A-g).

<Synthesis Example 8> The polyisocyanate prepolymer component (B) was synthesized as follows using the raw materials shown in Table 2. In a 2 L separable flask purged with nitrogen, the HDI oligomer coronate 2365 (N
CO% = 21.0 to 23.5, manufactured by Nippon Polyurethane Industry Co., Ltd., 385 g, and HDI prepolymer Coronate 2094 (NCO% = 15.4 to 16.8, manufactured by Nippon Polyurethane Industry Co., Ltd.), 133 g. Then, 0.20 g of dibutyltin dilaurate as a urethane-forming catalyst was accurately charged and uniformly stirred in a nitrogen stream in a mantle heater capable of adjusting the temperature.

4% of the dehydrated aromatic diol-free polyether diol Exenol 2020 was added thereto.
81 g was added and reacted at a temperature of 90 to 100 ° C. for 2 hours while uniformly stirring in a nitrogen stream. The finished polyisocyanate-based prepolymer component (Ba) had an isocyanate content of 8.5% and a viscosity at 25 ° C of 4200.
In mpa · s, the average number of functional groups in GPC analysis is 2.8.
Met.

<Synthesis Example 9> As a polyisocyanate-based prepolymer component (B), 45 g of hexamethylene diisocyanate and 0.1 g of dibutyltin dilaurate as a urethanization catalyst were placed in a nitrogen-substituted 2 L separable flask.
Charge 8 g, and in a mantle heater with adjustable temperature, charge 481 g of dehydrated Exenol 2020 in a nitrogen stream, react for 1 hour at a temperature of 90 to 100 ° C. with uniform stirring, and cool to 50 ° C. or lower, then HDI oligomer coronate 2365 (manufactured by Nippon Polyurethane Industry Co., Ltd.) 38
5g was added and it was made to react at 90-100 degreeC for 2 hours. The polyisocyanate-based prepolymer component (Bb) had an isocyanate content of 8.4% and a viscosity at 25 ° C. of 6%.
At 500 mpa · s, the average number of functional groups in GPC analysis is 2.
It was 4.

<Synthesis Example 10> As a comparative material for the polyisocyanate-based prepolymer component (B), 2 L substituted with nitrogen was used.
In a separable flask, 471 g of isophorone diisocyanate (manufactured by Daicel-Furus Co., Ltd.) and dibutyltin dilaurate as a urethane-forming catalyst, 0.40 g
Exenol 202, which had been charged with water and dehydrated in a nitrogen stream
0,1529g was added, and the temperature was 90 while stirring uniformly.
The reaction was carried out at -100 ° C for 3 hours. The obtained polyisocyanate prepolymer component (B-c) is bifunctional,
Isocyanate content is 5.4%, 25 ° C viscosity is 340
It was 0 mpa · s.

<Synthesis Example 11> As a comparative material for the polyisocyanate-based prepolymer component (B), 2 L substituted with nitrogen was used.
A separable flask was charged with 1706 g of Coronate 2094 (manufactured by Nippon Polyurethane Industry Co., Ltd.) and 0.40 g of dibutyltin dilaurate as a urethane-forming catalyst, and the mixture was uniformly stirred in a nitrogen stream and dehydrated in a nitrogen stream. Polyether polyol, exenol 153
0 (Mn = 1500, manufactured by Asahi Glass Urethane Co., Ltd.) 29
Charge 6 g, while stirring uniformly, the temperature 90 ~ 100
The reaction was carried out at 0 ° C for 2 hours. The polyisocyanate-based prepolymer component (Bd) thus obtained had an isocyanate content of 1
2.5%, 25 ° C viscosity is 53000mpa · s, G
The average number of functional groups in the PC analysis was 3.6.

[Preparation of Polyurethane Adhesive Composition] Table 3
As shown in, the polyol components (A-a) to (A-d) or the polyol-based prepolymer (A-e) synthesized in each of the above synthesis examples, and the polyisocyanate-based prepolymer component (B-a), ( B-b) was combined with the equivalent ratio R at a predetermined ratio to prepare polyurethane pressure-sensitive adhesive compositions (Examples 1 to 6).

Further, the polyol components (A-f) and (A-
g) and a polyisocyanate-based prepolymer component (B-
c) and (B-d) were combined in a predetermined ratio to prepare a polyurethane pressure-sensitive adhesive composition as a comparative material (Comparative Examples 1 to 1).
4).

[0084]

[Table 3]

[Evaluation of Adhesives] Ten types of polyurethane adhesive compositions prepared in Examples 1 to 6 and Comparative Examples 1 to 4 were used as the polyol component (A) or (A1) and the isocyanate component (B). After mixing with and using an applicator, the dry film thickness is about 25 μm on the 38 μm PET film.
Was coated on the adhesive sheet and heated to 120 ° C. for 2 minutes in a constant temperature bath to be processed into an adhesive sheet, and various tests shown below were conducted.

(1) Adhesive strength The adhesive sheet was roll-pressed to a stainless steel plate (SUS304 standard test plate) in accordance with JIS Z0237 at room temperature, and after 30 minutes, the peel strength was measured by a Shopper type peel tester (peeling angle 180 degrees, peeling speed 300 mm /
min). The adhesive strength was evaluated from the obtained peel strength. The evaluation standard of adhesive strength is as follows. Adhesiveness: ○: 1.0 N / 25 mm or more ×: less than 1.0 N / 25 mm

(2) Holding power The pressure-sensitive adhesive sheet was applied at room temperature to a stainless steel plate (SUS304 standard test plate) 25 mm x 2 in accordance with JIS Z0237.
The roll was pressure-bonded in an area of 5 mm, left at 70 ° C. for 20 minutes, a load of 1 kg was applied, and the time until falling or the deviation after 1 hour was measured.

(3) Transparency The transparency of the cured pressure-sensitive adhesive layer was visually evaluated. The evaluation criteria are as follows. Transparency ... ○: Transparent ×: There is turbidity

(4) The adhesive sheet having adhesive residue is roll-pressed at room temperature to a stainless steel plate (SUS304 standard test plate) according to JIS Z0237, left in a constant temperature bath at 40 ° C. for 24 hours, then cooled and peeled off. The adhesive residue was visually evaluated. Adhesive residue property ∘: No transfer of adhesive to the stainless steel plate ×: Transfer of adhesive is observed

[Evaluation Results] Table 3 shows the evaluation results of the above four items.
Shown in. From the table, the polyurethane pressure-sensitive adhesive composition according to the present invention shows that when a polyester diol is used as a diol component (Examples 1, 2 and 6), a polyether diol is used (Example 3), a polyester diol and a poly- In each case where the ether diol is used in combination (Example 4), good adhesive force and holding power are exhibited, and extremely good adhesiveness with no adhesive residue is exhibited, and it is excellent in transparency. I understand.

Among the diol components, Examples 1, 2 and 6 in which polyester diol was used particularly showed higher adhesive strength than Example 3 in which polyether diol was used. It is considered that this is because polyester diol structurally has a high cohesive force.

When the same diol component was used, when the diol component and the triol component were simply mixed (Example 1), and when both were pre-reacted to form the prepolymer (A1) (Example) It was confirmed that 5) and 5) have the same characteristics.

On the other hand, a polyester diol as a diol component, which did not contain an aromatic ring (Comparative Example 3), had an adhesive residue. This is probably because the cohesive force is reduced. Further, even in the case of a polyester diol having an aromatic ring, when a polyester diol containing no polyoxyalkylene group is used (Comparative Example 4),
Good transparency cannot be obtained. It is considered that this is because the compatibility with the polyether triol was lowered because it did not contain a polyoxyalkylene group.

Regarding the prepolymer (B1), when the average number of terminal isocyanate groups is 2.2 or less (Comparative Example 1), the crosslink density becomes small, the tackiness becomes too high, and the paste is re-peeled. It becomes easy to remain. On the other hand, when the average number of terminal isocyanate groups is 3.0 or more, the crosslink density becomes too high and the tackiness becomes poor.

[Evaluation of Laminated Adhesive Sheet] As shown in Table 4, the polyol component (A-a) of Synthesis Example 1 and the polyisocyanate prepolymer component (B-a) of Synthesis Example 8 were used.
In combination with the above, three types of polyurethane adhesive compositions having different adhesive strengths were prepared by changing the compounding ratio R of both, and using these adhesive compositions, a three-layer type adhesive sheet (label) Was prepared and its characteristics were evaluated. A schematic configuration diagram of the three-layer pressure-sensitive adhesive sheet is shown in FIG.

The three-layer type pressure-sensitive adhesive sheet 1 comprises three sheet materials, a first sheet material 2, a second sheet material 3 and a third sheet material 4, which are laminated from the surface side of an adherend via an adhesive agent, On the adherend side of one sheet material 2, that is, on the back surface side of the first sheet material 2, an adhesive layer for adhering the pressure-sensitive adhesive sheet 1 to the adherend is formed. In this example, the polyurethane pressure-sensitive adhesive composition according to the present invention is used so that the adhesive layer can also be peeled off, whereby the first pressure-sensitive adhesive layer 5 is formed. In the first sheet material 2, a first printing layer 2b is formed on the surface side of a first base material 2a made of a PET film having a thickness of 25 μm, and an overcoat layer (protective layer) for protecting the first printing layer 2b is further formed thereon. First coat layer 2c)
Is formed.

Similarly, the second sheet material 3 has a thickness of 38 μm.
The second printing layer 3b and the coat layer 3c are provided on the front surface side of the second base material 3a made of a thick PET film, and the third sheet material 4 is a third base material 4a made of a PET film having a thickness of 38 μm. The print layer 4b and the coat layer 4c are provided on the front surface side of the.

The second adhesive layer 6 is non-peelable coated on the back side of the second sheet material 3, and the third adhesive layer 7 is non-peelable coated on the back side of the third sheet material 4. ing. The second adhesive layer 6 is attached on the coat layer 2c on the surface of the first sheet material 2, and the third adhesive layer 7 is attached on the coat layer 3a on the surface of the second sheet material 3. Has become. Hereinafter, a method for manufacturing the adhesive sheet 1 will be described.

First, the first pressure-sensitive adhesive layer 5 to be adhered to the adherend.
As described above, by coating the first layer pressure-sensitive adhesive composition shown in Table 4 on the first substrate 2a side of the first sheet material 2 so that the dry film thickness becomes 25 μm, and drying at 120 ° C. for 2 minutes. It was formed and a release paper was attached to the adhesive surface. Similarly, for the second adhesive layer 6, the second layer adhesive composition having a dry film thickness of 2
The second sheet material 3 was coated on the second substrate 3b side so as to have a thickness of 0 μm, dried at 120 ° C. for 2 minutes, and then a release paper was attached to the adhesive surface. The second pressure-sensitive adhesive layer 6 was peeled off when used as a label to form a non-tacky portion for the mouth, so the pressure-sensitive adhesive composition was applied in a streak shape. Similarly to the second pressure-sensitive adhesive layer 6, the third pressure-sensitive adhesive layer 7 contains the third layer pressure-sensitive adhesive composition so that the dry film thickness becomes 20 μm.
3rd base material 4a side was applied in a streak shape and dried at 120 ° C. for 2 minutes, and then a release paper was attached to the adhesive surface.

The sheet material was printed on the surface of the substrate with UV curable ink (UV161 manufactured by T & K TOKA Co., Ltd.), and after UV curing, a UV curable transparent overcoat (manufactured by T & K TOKA Co., Ltd.) was used. UV L
TP varnish) was printed and UV cured. When coating the adhesive, after forming a sheet material by applying a printing and protective overcoat to the substrate,
The surface of the base material side may be coated with the pressure-sensitive adhesive composition, or after coating the pressure-sensitive adhesive composition on the back surface side of the base materials 2a, 3a, 4a, an overcoat for printing and protection on the front surface side. May be given.

After producing three kinds of sheet materials as described above, the second pressure-sensitive adhesive layer 6 was attached onto the first coat layer 2c while peeling off the release paper. Similarly, the second coat layer 3
The third pressure-sensitive adhesive layer 7 was adhered onto c while peeling off the release paper. This was punched by a punching machine to obtain a three-layer type adhesive label 1. Table 4 shows the results of measuring the adhesive strength of the first to third adhesive layers to the stainless steel plate. Also, peel off the release paper of the first adhesive layer 5 of the label and attach it to a glass bottle,
The peeling force of each layer was measured after standing for 24 hours. The results are shown in Table 4.

From Table 4, the first layer having an NCO / OH ratio of 0.60 in the adhesive composition has an adhesive force of 8.04 N / 25.
mm, and the peeling force is 10.78 N / 25 mm, which shows excellent adhesiveness. Further, the NCO / OH ratio is 0.7, 0.
By increasing the value to 8, it is possible to suppress the adhesiveness, and it is possible to make a large difference between the adhesive force and the peeling force of the first adhesive layer 5.

Actually, peeling-pasting of each pressure-sensitive adhesive layer was repeated 10 times using hands, but neither was found to be lifted or peeled off on the lower layer side, and it was confirmed that it was excellent as a laminated pressure-sensitive adhesive sheet. It was Further, in this example, the surfaces of the sheet materials 2, 3, and 4 to be adhered to the adhesive layers 5, 6, and 7 are only overcoated for protection, and no release agent is used. , No glue residue was found.

[0104]

[Table 4]

[Evaluation of Transparent Adhesive Sheet] A transparent adhesive sheet (label) was prepared using the polyol component (Aa) of Synthesis Example 1 and the polyisocyanate prepolymer component (Ba) of Synthesis Example 8. It was produced and its characteristics were evaluated.

A pressure sensitive adhesive was prepared by blending the polyol component (Aa) with the polyisocyanate prepolymer component (Ba) of Synthesis Example 8 so that R (NCO / OH equivalent ratio) was 0.7. A composition was prepared, which was made into a transparent PE having a thickness of 38 μm.
The T film was coated so that the film thickness when dried was 20 μm. Then, release paper was stuck on the adhesive layer formed by drying at 120 ° C. for 2 minutes to obtain a label base paper.

Next, characters are printed on the PET surface of the label base paper with a UV curable ink (UV161 manufactured by T & K TOKA Co., Ltd.), and after UV curing, a UV curable transparent overcoat (UV L manufactured by T & K TOKA Co., Ltd.).
TP OP varnish) was printed and UV cured.

As a comparative material, a widely used isocyanate (Coronate L; a reaction product of toluene diisocyanate and trimethylolpropane, manufactured by Nippon Polyurethane Industry Co., Ltd.) was used, and the polyol component (A-a of Synthesis Example 1) was used. ) Is added so that the NCO / OH ratio is 0.7, and the film thickness is 20
The coating was dried to a thickness of μm. Further, a printing layer and an overcoat layer were provided on the PET surface in the same manner as above.

The two types of transparent adhesive labels produced as described above were cut into the same size, the release paper was peeled off, and the label was attached to a glass bottle. This was placed in a fade meter and irradiated with ultraviolet rays for 500 hours. As a result, the label produced from the pressure-sensitive adhesive composition using the polyisocyanate component Ba of the present invention did not show yellowing or turbidity even after UV irradiation for 500 hours. On the other hand, a label made of a pressure-sensitive adhesive composition using Coronate L, which is a general-purpose polyisocyanate, started to turn yellow at 50 hours and deeply turned yellow at 500 hours, and was also turbid.

From the above, the pressure-sensitive adhesive sheet using the pressure-sensitive adhesive composition according to the present invention has excellent transparency and little discoloration over time, and therefore, when used as a transparent label, the visibility of the displayed content can be maintained well. Was confirmed. Therefore, in the three-layer pressure-sensitive adhesive sheet produced in the preceding paragraph, if a printing layer is provided on the back side of each of the base materials 2, 3, 4 and the pressure-sensitive adhesive composition is applied thereon, the visibility is sufficiently high. It is possible to obtain a spread type label.

[0111]

As is apparent from the above description, according to the present invention, as the polyol component (A) or (A1), a polyether and / or polyester having an aromatic ring and a polyoxyalkylene group in the molecule is used. Diol,
Since a mixture of a diol component containing as a main component and polyether triol in a predetermined ratio was used, it is excellent in adhesiveness, transparency and weather resistance, does not leave adhesive residue, and is a reusable urethane that can be repeatedly used. An adhesive composition can be obtained.

A pressure-sensitive adhesive sheet obtained by applying the above-mentioned pressure-sensitive adhesive composition to a sheet has excellent adhesiveness and weather resistance and does not cause adhesive residue, so a reflective layer is provided on the surface of the sheet. As a result, it is possible to obtain a reflection sheet that can be attached to a window of a house or a vehicle to prevent the occurrence of dew condensation, cut strong sunlight, and easily peel off when unnecessary.

Further, by adding an ultraviolet absorber or a colorant to the sheet, it is possible to obtain a light-reducing sheet having good visibility of the outside scenery because the adhesive has excellent transparency.

Further, in the case of producing a laminated type pressure-sensitive adhesive sheet in which the sheet is composed of a plurality of base materials, the pressure-sensitive adhesive composition according to the present invention is used to prepare a plurality of pressure-sensitive adhesive compositions having different adhesive strengths. Since a large difference in adhesive strength can be obtained by interposing a material having a low adhesive strength in order from the lower layer side, it is possible to obtain a laminated adhesive sheet in which only necessary layers can be peeled off. You can

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a three-layer adhesive sheet.

[Explanation of symbols]

1 Adhesive sheet 2, 3, 4 sheet material 2a, 3a, 4a base material 2b, 3b, 4b Printed layer 2c, 3c, 4c protective overcoat layer 5, 6, 7 Adhesive layer

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shoichi Akita             622 Chiyo, Taharahoncho, Isojo-gun, Nara Co., Ltd.             Fujitac Nara factory F-term (reference) 4J004 AA14 AB01 CC03 FA01                 4J034 DB04 DB05 DF01 DF02 DF12                       DF21 DG02 DG23 HC03 HC22                       HC61 HC71 HC73 JA02 JA44                       JA46 KC17 KD02 QA02 QA05                       QC03 QC08 RA05 RA08                 4J040 EF131 EF282 EF321 EF322                       JA09 JB09

Claims (9)

[Claims] 1. A polyol component (A) containing a diol component containing a polyether diol having an aromatic ring and a polyoxyalkylene group as a main component in the molecule and a polyether triol, or the polyol component (A). ) Is mixed with an aliphatic or alicyclic diisocyanate in an amount less than the reaction equivalent and reacted, and a prepolymer (A1) having a hydroxyl group at the terminal, an aliphatic or alicyclic polyisocyanate (B), or the polyisocyanate ( B) was used,
Prepolymer (B1) having an isocyanate group at the terminal
A polyurethane adhesive composition obtained by reacting with. 2. A polyol component (A) containing a diol component containing a polyester diol having an aromatic ring and a polyoxyalkylene group as a main component in the molecule and a polyether triol, or the polyol component (A). And a prepolymer (A1) having a hydroxyl group at the terminal, which is obtained by mixing and reacting with an aliphatic or alicyclic diisocyanate in an amount less than the reaction equivalent, and an aliphatic or alicyclic polyisocyanate (B), or the polyisocyanate (B ) Was used,
Prepolymer (B1) having an isocyanate group at the terminal
A polyurethane adhesive composition obtained by reacting with. 3. A diol component containing a mixture of a polyether diol having an aromatic ring and a polyoxyalkylene group in the molecule and a polyester diol having an aromatic ring and a polyoxyalkylene group in the molecule as a main component. A polyol component (A) containing a polyether triol, or a prepolymer (A1) having a hydroxyl group at the terminal, which is obtained by mixing the polyol component (A) with an aliphatic or alicyclic diisocyanate in a reaction amount less than the reaction equivalent and reacting the mixture. When,
Aliphatic or alicyclic polyisocyanate Aliphatic or alicyclic polyisocyanate (B), or by reacting the polyisocyanate (B) with a prepolymer (B1) having an isocyanate group at the end The resulting polyurethane adhesive composition. 4. The polyurethane pressure-sensitive adhesive composition according to claim 1, 2 or 3, wherein the mixing ratio of the diol component and the triol is 10: 1 to 1: 1 in terms of equivalent ratio of hydroxyl groups. 5. A pressure-sensitive adhesive sheet obtained by applying the polyurethane pressure-sensitive adhesive composition according to claim 1 to a sheet material. 6. The pressure-sensitive adhesive sheet according to claim 5, wherein the polyurethane pressure-sensitive adhesive composition is applied onto the printing surface of the sheet material. 7. A plurality of the sheet materials are arranged in layers,
A pressure-sensitive adhesive layer made of the polyurethane pressure-sensitive adhesive composition is interposed between the sheet materials, and the pressure-sensitive adhesive layer is non-peelably applied to one of the sheet materials on both sides of the pressure-sensitive adhesive layer and the other side of the sheet material. A laminate type pressure-sensitive adhesive sheet, which is releasably attached to a sheet material, and an adhesive layer for adhering to an adherend is applied to the back surface of the sheet material on the lower layer side, wherein the adhesive layer is an adhesive layer. The adhesive strength is set to be lower than that of the agent layer.
Alternatively, the pressure-sensitive adhesive sheet according to item 6. 8. The sheet material is arranged in layers of three or more, and a pressure-sensitive adhesive layer made of the polyurethane pressure-sensitive adhesive composition is interposed between each sheet material. Among them, a laminated pressure-sensitive adhesive sheet which is non-peelingly applied to a sheet material on one side and is peelably attached to a base material on the other side, wherein the pressure-sensitive adhesive layer has the lowest adhesive strength of the lowermost layer. The pressure-sensitive adhesive sheet according to claim 5 or 6, wherein the pressure-sensitive adhesive sheet is set to be stronger and have lower adhesive strength toward the upper layer side. 9. The pressure-sensitive adhesive sheet according to claim 5, wherein the sheet material is transparent.