JP2000256640A - Polyurethane adhesive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition which is free from leaving of the adhesive when the coated material is peeled off by blending a polyfunctional isocyanate compound with a polyurethane polyol having terminal hydroxyl groups, obtained through the reaction of a polyester polyol, a polyether polyol and an organic polyisocyanate in the presence of a specified number of catalysts having a specified ratio of relative activities. SOLUTION: Two catalysts are used which have a ratio of relative activities of (2 to 60):1, preferably (2 to 30):1. One of the catalysts preferably comprises tin 2-ethylhexanoate, The weight ratio of other organometallic catalyst (e.g. dibutyltin laurate) to 2-ethylhexanoate is preferably less than 1:1 more preferably (0.1 to 0.9):1. The amount of the catalysts used is preferably 0.01-1.0 wt.% based on the total of the polyols comprising a polyester polyol and a polyether polyol and the organic polyisocyanate. It is desirable that part of the polyols have a molecular weight of 2,000 to 4,000 and are trifunctional.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a polyurethane pressure-sensitive adhesive composition which is useful for pressure-sensitive adhesive tapes, pressure-sensitive labels, pressure-sensitive adhesive seals, cosmetic pressure-sensitive adhesive sheets, non-slip sheets, double-sided pressure-sensitive adhesive tapes and the like, and has excellent removability.

[0002]

2. Description of the Related Art Conventional acrylic tapes, labels, seals, decorative sheets, non-slip sheets,
Coated products such as double-sided adhesive tape have excellent adhesive strength,
When it was peeled off from the adherend after being adhered to the adherend because the re-adhesive property was not sufficient, there was a problem that adhesive remained on the adherend and the adhesive strength increased, and re-pasting was not possible. In addition, there is a problem that when the adhesive strength is reduced to a small level, the holding power is lost, and the adhesive strength varies greatly depending on the amount of the curing agent.

On the other hand, tapes using urethane-based adhesives,
Coatings such as labels, seals, cosmetic sheets, non-slip sheets, and double-sided adhesive tapes can satisfy various physical properties required for coatings, but increase the viscosity of resin solutions, control reactions, and reduce raw material costs. There was a problem. In particular, it was difficult to control the compatibility and crosslinkability of the resin solution as the reaction progressed.

[0004]

DISCLOSURE OF THE INVENTION The present invention relates to a method for removing adhesives when peeling a coated article using an acrylic pressure-sensitive adhesive, increasing adhesive strength,
An object of the present invention is to provide a polyurethane pressure-sensitive adhesive composition in which the above-mentioned various drawbacks of a urethane-based pressure-sensitive adhesive are improved, in which stable weak adhesion is hardly obtained.

[0005]

Conventionally, two or more kinds of polyols such as polyester polyol and polyether polyol having different compatibility and reactivity and an organic polyisocyanate compound have been reacted in the presence of a single catalyst. . In this system, there was a problem that the reaction solution often became turbid or gelled. In particular, it is remarkable when the reaction temperature is 100 ° C. or lower. Therefore, as a result of various studies of reaction conditions, it was found that a polyurethane resin can be obtained by using two types of catalysts without causing the reaction solution to become turbid or gelled.

That is, the first invention has a hydroxyl group at a terminal obtained by reacting a polyester polyol with a polyether polyol and an organic polyisocyanate using two kinds of catalysts having a relative activity ratio of 2 to 60. The present invention relates to a polyurethane pressure-sensitive adhesive composition obtained by blending a polyfunctional isocyanate compound (B) with a polyurethane polyol (A) having the same. The second invention relates to the polyurethane pressure-sensitive adhesive composition according to the first invention, wherein two types of catalysts having a relative activity ratio of 2 to 30 are used. The third invention relates to the polyurethane pressure-sensitive adhesive composition according to the second invention, wherein one of the two catalysts is tin 2-ethylhexanoate.

A fourth invention is characterized in that a part of the polyol comprising a polyester polyol and a polyether polyol has a molecular weight of 2,000 to 4,000 and is trifunctional. Or a polyurethane pressure-sensitive adhesive composition as described above.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION

Known polyester polyols are used as the polyester polyol used in the present invention. Terephthalic acid, adipic acid, azelaic acid,
Sebacic acid, phthalic anhydride, isophthalic acid, trimellitic acid, and the like, and glycol components such as ethylene glycol, propylene glycol, diethylene glycol, butylene glycol, 1,6-hexane glycol, 3-methyl-1,5-pentanediol, 3,3 '
-Dimethylol heptane, polyoxyethylene glycol, polyoxypropylene glycol, 1,4-butanediol, neopentyl glycol, butylethylpentanediol, and glycerin, trimethylolpropane, pentaerythritol and the like as polyol components. Other examples include polyester polyols obtained by ring-opening polymerization of lactones such as polycaprolactone, poly (β-methyl-γ-valerolactone) and polyvalerolactone. The molecular weight of the polyester polyol can be used from a low molecular weight to a high molecular weight. The use amount thereof is preferably 1 to 50 mol% in the polyol constituting the polyurethane polyol (A).

As the polyether polyol used in the present invention, a known polyether polyol is used. For example, propylene glycol, ethylene glycol, glycerin, using a low molecular weight polyol such as trimethylolpropane as an initiator, ethylene oxide, propylene oxide, butylene oxide, polyether polyol obtained by polymerizing an oxirane compound such as tetrahydrofuran, specifically Specifically, those having two or more functional groups, such as polypropylene glycol, polyethylene glycol, and polytetramethylene glycol, are used. The molecular weight of the polyether polyol can be used from a low molecular weight to a high molecular weight. The use amount thereof is preferably 1 to 80 mol% in the polyol constituting the polyurethane polyol (A).

In the present invention, a resin having high cohesive strength can be obtained by partially using a polyol having three or more functional groups. Preferably, it is a polyol having a molecular weight of 1,000 to 5,000 and a functionality of 3 or more. Polyols having a molecular weight of 1,000 or less and having three or more functional groups have high reactivity and are easily gelled.
In addition, a polyol having a molecular weight of 5,000 or more and having three or more functional groups has poor reactivity, and further, the cohesive force of the polyurethane polyol (A) itself becomes small. More preferably, a trifunctional polyol having a molecular weight of 2,000 to 4,000 is partially used.

In the present invention, if necessary, some glycols such as ethylene glycol, 1,4-butanediol, neopentyl glycol, butylethylpentanediol, glycerin, trimethylolpropane and pentaerythritol, ethylenediamine, N- Polyvalent amines such as aminoethylethanolamine, isophoronediamine and xylylenediamine can also be used in combination.

The organic polyisocyanate compound used in the present invention includes known aromatic polyisocyanates, aliphatic polyisocyanates, araliphatic polyisocyanates, and alicyclic polyisocyanates.

As aromatic polyisocyanates, 1,3
-Phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,4-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate,
2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4′-toluidine diisocyanate, 2,4,6-triisocyanate toluene, 1,
Examples thereof include 3,5-triisocyanatebenzene, dianisidine diisocyanate, 4,4'-diphenylether diisocyanate, and 4,4 ', 4 "-triphenylmethane triisocyanate.

As the aliphatic polyisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, Examples include 2,4,4-trimethylhexamethylene diisocyanate.

As the araliphatic polyisocyanates, ω, ω′-diisocyanate-1,3-dimethylbenzene, ω, ω′-diisocyanate-1,4-dimethylbenzene, ω, ω′-diisocyanate-1,4-diethylbenzene , 1,4-tetramethylxylylene diisocyanate, 1,3-tetramethyl xylylene diisocyanate, and the like.

Examples of the alicyclic polyisocyanate include 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl-2 , 4-cyclohexanediisocyanate, methyl-
2,6-cyclohexane diisocyanate, 4,4'-
Methylene bis (cyclohexyl isocyanate), 1,
4-bis (isocyanatomethyl) cyclohexane,
1,4-bis (isocyanatomethyl) cyclohexane and the like can be mentioned.

A trimethylolpropane adduct of the above-mentioned polyisocyanate, a buret reacted with water, a trimer having an isocyanurate ring, and the like can also be used in combination.

Among the pressure-sensitive adhesives, when weather resistance is important, aliphatic and alicyclic polyisocyanates are particularly preferred among the above.

As the polyisocyanate used in the present invention, 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate) and the like are preferable.

As the catalyst used in the present invention, a known catalyst can be used. For example, tertiary amine compounds, organometallic compounds and the like can be mentioned.

Examples of the tertiary amine compound include triethylamine, triethylenediamine, 1,8-diazabicyclo (5,4,0) -undecene-7 (DBU) and the like.

The organometallic compounds include tin compounds and non-tin compounds.

As the tin compound, dibutyltin dichloride, dibutyltin oxide, dibutyltin dibromide,
Dibutyltin dimaleate, dibutyltin dilaurate (D
BTDL), dibutyltin diacetate, dibutyltin sulfide, tributyltin sulfide, tributyltin oxide, tributyltin acetate, triethyltin ethoxide, tributyltin ethoxide, dioctyltin oxide, tributyltin chloride, tributyltin trichloroacetate, 2-ethylhexanoic acid Tin etc. are mentioned.

Examples of the non-tin compounds include titanium compounds such as dibutyl titanium dichloride, tetrabutyl titanate and butoxy titanium trichloride, and lead compounds such as lead oleate, lead 2-ethylhexanoate, lead benzoate and lead naphthenate. Iron, such as iron, 2-ethylhexanoate and iron acetylacetonate; cobalt, such as cobalt benzoate and cobalt 2-ethylhexanoate; zinc, such as zinc naphthenate and zinc 2-ethylhexanoate; zirconium naphthenate And the like.

The relative activity of the catalyst is defined as 1 based on the reactivity to hydroxyl groups when no catalyst is used.
Is defined as For example, Ind. Eng. Che
m. (52, 609, 1960), according to the Handbook of Crosslinking Agents (Saiseisha, Shinzo Yamashita, Tosuke Kaneko), etc., triethylamine 11, cobalt naphthenate 23, stannous chloride 6
8, tetra-n-butyltin 82, stannic chloride 99, trimethyltin hydroxide 1800, dimethyltin dichloride 21
00, dibutyltin dilaurate 37000 and tin 2-ethylhexanoate 95,000.

When these catalysts are used alone in a system in which two kinds of polyols of a polyester polyol and a polyether polyol are present, particularly when a part contains a trifunctional component, gelation or reaction may occur due to the difference in reactivity. The problem that the solution becomes turbid tends to occur. At this time, by simultaneously using two types of catalysts, the reaction rate can be controlled, and these problems can be solved. As a combination, two types of catalysts having different relative activities are used, and the criterion is a ratio of the relative activities. The ratio of the relative activities is represented by a larger relative activity / a smaller relative activity. In the present invention, it is necessary that the ratio of the relative activities is 2 to 60. Preferably, the relative activity ratio is between 2 and 30. When the ratio of the relative activities is 2 or less, the activities are close to each other, so that the gelation and the turbidity of the reaction solution easily occur as in the case where the same catalyst is used. On the other hand, when the ratio is 60 or more, one activity becomes dominant, and the effect of the combined use is reduced.

The two types of catalysts are more preferably both organometallic catalysts having a relative activity ratio of 2 to 30.
Preferably, one of them is to use tin 2-ethylhexanoate. The compounding ratio is that other organometallic catalyst / tin 2-ethylhexanoate <1 by weight. Preferably 0.
1 to 0.9. These catalysts are used in an amount of 0.01 to 1: 1 based on the total amount of the polyol and the organic polyisocyanate.
0% by weight is preferred.

As the polyfunctional isocyanate compound (B) used in the present invention, the above-mentioned organic polyisocyanate compounds and their trimethylolpropane adducts,
A buret body reacted with water, a trimer having an isocyanurate ring, or the like is used.

The mixing ratio of the polyurethane polyol (A) and the polyfunctional isocyanate (B) used in the present invention is 1 to 20 parts (B) per 100 parts (parts by weight) of (A). If it is 1 part or less, the cohesive strength decreases, and if it is 20 parts or more, the adhesive strength decreases. Preferably it is 2 to 10 parts.

The reaction temperature for obtaining the polyurethane polyol (A) of the present invention is preferably 100 ° C. or lower. More preferably, the temperature is from 85C to 95C. When the reaction temperature is 100 ° C. or higher, it is difficult to control the reaction rate and the crosslinked structure, and it is difficult to obtain a polyurethane polyol (A) having a predetermined molecular weight and a chemical structure.

As the solvent used in the present invention, known solvents can be used. Examples include methyl ethyl ketone, ethyl acetate, toluene, xylene, acetone and the like. Toluene is particularly preferred in view of the solubility of the polyurethane polyol (A) and the boiling point of the solvent.

The polyurethane pressure-sensitive adhesive according to the present invention may contain, if necessary, a filler such as talc, calcium carbonate, titanium oxide, a tackifier, a colorant, an ultraviolet absorber, an antioxidant, an antifoaming agent, and a light stabilizer. And the like.

The polyurethane pressure-sensitive adhesive according to the present invention is used by being applied to a base material such as a plastic film, a plastic sheet, polyurethane, paper, or polyurethane foam. The coated product is suitably used as a tape, a label, a seal, a cosmetic sheet, a non-slip sheet, a double-sided adhesive tape, and the like.

A synthesis example will be described below.

Synthesis Example 1 Polyester polyol P-1 was placed in a four-necked flask equipped with a stirrer, reflux condenser, nitrogen inlet, thermometer, and dropping funnel.
010 (bifunctional, molecular weight 1,000, manufactured by Kuraray Co., Ltd.) 78 g, polyether polyol PP-2000
(Bifunctional, molecular weight 2,000, manufactured by Sanyo Chemical Industries, Ltd.) 187 g, isophorone diisocyanate (manufactured by Huls Japan KK) 35 g, toluene 200 g, tin 2-ethylhexanoate 0.05 g as catalyst, trimethyltin hydroxide 0 After charging 0.05 g, the temperature was gradually raised to 90 ° C., and the reaction was carried out for 3 hours. The residual isocyanate group is confirmed by an infrared spectrophotometer (IR). If the remaining isocyanate group disappears, the reaction is terminated and cooled. This reaction solution was colorless and transparent, had a solid content of 60%, had a viscosity of 3,100 cps, and had an MN (number average molecular weight) of 14,00.
0, MW (weight average molecular weight) 45,000.

Synthesis Example 2 Polyester polyol P-2 was placed in a four-necked flask equipped with a stirrer, a reflux condenser, a nitrogen inlet, a thermometer, and a dropping funnel.
010 (bifunctional, molecular weight 2,000, manufactured by Kuraray Co., Ltd.) 99 g, polyether polyol G-3000 (3
Functionality, molecular weight 3,000, manufactured by Asahi Denka Co., Ltd.) 179
g, 22 g of isophorone diisocyanate (manufactured by Huls Japan K.K.), 200 g of toluene, 0.05 g of dimethyltin dichloride as a catalyst, 0.0 g of tetra-n-butyltin
5 g is charged, the temperature is gradually raised to 90 ° C., and the reaction is carried out for 5 hours. The residual isocyanate group is confirmed by IR, and if it has disappeared, the reaction is terminated and cooled. The reaction solution was colorless and transparent, solid content 60%, viscosity 3,200 cps, MN 14,500,
The MW was 57,000.

Synthesis Example 3 Polyester polyol P-2 was placed in a four-necked flask equipped with a stirrer, a reflux condenser, a nitrogen inlet, a thermometer, and a dropping funnel.
010 (bifunctional, molecular weight 2,000, manufactured by Kuraray Co., Ltd.) 99 g, polyether polyol G-3000 (3
Functionality, molecular weight 3,000, manufactured by Asahi Denka Co., Ltd.) 179
g, isophorone diisocyanate (manufactured by Huls Japan KK) 22 g, toluene 200 g, 2-
0.05 g of tin ethylhexanoate and 0.05 g of dibutyltin dilaurate are charged, and the temperature is gradually raised to 90 ° C. to carry out a reaction for 5 hours. The residual isocyanate group is confirmed by IR, and if it has disappeared, the reaction is terminated and cooled. The reaction solution was colorless and transparent, solid content 60%, viscosity 3,200 cps, MN14,
000, MW 56,000.

Synthesis Example 4 Polyester polyol P-2 was placed in a four-necked flask equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer, and dropping funnel.
010 (bifunctional, molecular weight 2,000, manufactured by Kuraray Co., Ltd.) 99 g, polyether polyol G-3000 (3
Functionality, molecular weight 3,000, manufactured by Asahi Denka Co., Ltd.) 179
g, 22 g of isophorone diisocyanate (manufactured by Huls Japan KK), 200 g of toluene, 0.05 g of stannic chloride and 0.05 g of stannous chloride as a catalyst, and 9
The temperature is gradually raised to 0 ° C., and the reaction is carried out for 5 hours. The residual isocyanate group is confirmed by IR, and if it has disappeared, the reaction is terminated and cooled. The reaction solution was colorless and transparent, solid content was 60%, viscosity was 4,500 cps, MN was 13,000, and MW was 59,00.
It was 0.

Synthesis Example 5 400 g of ethyl acetate and 50 g of toluene were charged into a four-necked flask equipped with a stirrer, a reflux condenser, a nitrogen introduction tube, a thermometer, and a dropping funnel.
A half amount of a monomer consisting of 60 g of ethylhexyl acrylate and 10 g of 2-hydroxyethyl acrylate was charged. The temperature was raised to 80 ° C. in a stream of nitrogen gas, and 0.3 g of benzoyl peroxide was added. Next, the remaining monomer is
The solution was added dropwise over a period of time, and after the addition was completed, benzoyl peroxide was added in a concentration of 0.1 mL.
3 g was added and reacted for 3 hours. 5,000 cp viscosity
s.

[0041]

EXAMPLES Examples and comparative examples will be described below.

Table 1 shows the composition of the polyurethane pressure-sensitive adhesive.

Table 2 shows the results of the adhesion test and the holding test.

Table 3 shows the results of the ball tack test and the removability test.

The test items are as follows. Coating method: 25μ dry coating film of the above adhesive solution on release paper
m and dried at 100 ° C. for 2 minutes to prepare a coated product. After aging at room temperature for one week, physical properties were measured. Adhesive strength: Adhesive sheet is made of 2mm thick stainless steel plate (SU
S304) at 23 ° C.-65% RH, roll-pressed according to JIS, and after 20 minutes, peel strength (180 ° peel, pulling speed 300 m) with a shopper type peel tester.
m / min).

Holding force: A pressure-sensitive adhesive sheet was stuck on a stainless steel plate (SUS304) having a thickness of 2 mm in an area of 25 mm × 25 mm, roll-pressed in accordance with JIS, left at 40 ° C. for 20 minutes, applied with a load of 1 kg, and dropped. The number of seconds required to perform the measurement or the deviation after 60 minutes was measured. Ball tack: J. 2 by Dow type rolling ball method
It was measured under the conditions of 3 ° C. and 65% RH. Peelability: Stainless steel plate (SUS304),
After adhering to a glass plate, it was left under conditions of 40 ° C.-65% RH, cooled to 23 ° C.-65% RH, peeled off, and visually evaluated for adhesive residue. After peeling, ◎ indicates no adhesive transfer to the adherend, ○ indicates very slight transfer, △ indicates partial transfer, and × indicates complete transfer.

[0047]

[Table 1]

The polyfunctional isocyanate compound (B) was blended with 100 g of the solid content of the polyurethane reactant (A).
Of solids was added. Polyfunctional isocyanate compound (B) Takenate D-160N (hexamethylene diisocyanate-trimethylolpropane adduct), manufactured by Takeda Pharmaceutical Company Limited

[0049]

[Table 2]

[0050]

[Table 3]

Substrate: PET (polyethylene terephthalate) film thickness; 25 μ PU (polyurethane) film thickness; 50 μ * N. C. : Non-creep * S. D. : Slip down

From the above results, it can be seen that the coated product using the polyurethane pressure-sensitive adhesive composition according to the present invention is excellent in adhesive strength, holding power and removability.

[0053]

According to the present invention, a resin free from gelation and poor compatibility can be obtained by performing urethane synthesis in the presence of two types of catalysts having a relative activity ratio of 2 to 60. The urethane pressure-sensitive adhesive composition using the resin has less adhesive residue than the acrylic pressure-sensitive adhesive and is excellent in removability.

Continued on front page F-term (reference) 4J004 AA14 AA17 AB01 CA02 CA06 CB02 CB04 CC02 FA01 FA10 4J034 BA07 DB04 DB05 DB07 DC02 DC06 DC12 DC35 DC43 DC50 DF01 DF16 DF20 DF21 DF22 DG03 DG04 DG06 HA01 HA07 HC08 HC03 HC12 HC12 HC12 HC64 HC71 HC73 JA43 JA44 KA01 KB04 KC16 KC17 KC18 KC35 KD02 KD04 KD08 KD21 KD24 QA05 QB10 QB13 QC05 RA08 4J040 EF101 EF111 EF131 HB20 HB24 HB27 HC01 HC03 HC23 HD41 HD42 JA09 JB09 QA01 LA01

Claims (4)

[Claims] 1. A polyurethane polyol having a hydroxyl group at a terminal obtained by reacting a polyester polyol with a polyether polyol and an organic polyisocyanate using two kinds of catalysts having a relative activity ratio of 2 to 60 (A). And a polyfunctional isocyanate compound (B). 2. The polyurethane pressure-sensitive adhesive composition according to claim 1, wherein two kinds of catalysts having a relative activity ratio of 2 to 30 are used. 3. The polyurethane pressure-sensitive adhesive composition according to claim 2, wherein one of the two catalysts is tin 2-ethylhexanoate. 4. A polyol comprising a polyester polyol and a polyether polyol having a molecular weight of 2,0.
The polyurethane pressure-sensitive adhesive composition according to any one of claims 1 to 3, wherein the number is from 00 to 4,000 and trifunctional.