JP2023038422A - polyurethane adhesive - Google Patents

Abstract

To solve below problems: the fact that an adhesive increases in adhesive strength with time is also a common issue for any type of adhesive, there is a method for adding an ester compound to a polyurethane polyol as a method for suppressing the increase in adhesive strength with time in a polyurethane adhesive, however, it has not been sufficiently effective in suppressing the increase in adhesive strength with time after glass lamination and in addition, when an adhesive was peeled off from an adherend, it was confirmed that there was a case where an adhesive component was migrated to the adherend side.SOLUTION: There is provided a polyurethane adhesive which comprises at least a polyurethane polyol (A) synthesized from a polyol compound and a polyisocyanate compound and an ether ester compound (B) represented by the formula (1), wherein the polyurethane polyol (A) contains 46 pts.mass or more and 100 pts.mass or less of a polyether polyol compound in 100 pts.mass of a polyol compound as a constituent material.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a polyurethane pressure-sensitive adhesive used in manufacturing equipment related to image display devices.

Polyurethane adhesives range from weak to strong adhesives, and are used as an adhesive film to protect the surface of image display devices from friction that can cause scratches and damage, as well as dust adsorption during the manufacturing of image display devices. As a display protective film, it is possible to protect the image quality of the display device without impairing it.
A method of adding an ester compound to a polyurethane polyol is known as a method for adjusting adhesive strength and wettability to a substrate and for suppressing an increase in adhesive strength over time.

Japanese Patent Application Laid-Open No. 2011-190420 JP 2015-151429 A

Patent Documents 1 and 2 have room for improvement in increasing the adhesive strength after the heat resistance test from the initial adhesive strength.

A problem common to all types of pressure-sensitive adhesives is that the pressure-sensitive adhesive strength increases over time.
Among polyurethane pressure-sensitive adhesives, as a method of suppressing the increase in adhesive strength over time, there is a method of adding an ester compound to a polyurethane polyol. However, the effect of suppressing the increase in adhesive strength over time after glass bonding was not sufficient. It has also been confirmed that when the adhesive is peeled off from the adherend, the adhesive components migrate to the adherend. It is an object of the present invention to solve these problems.

A polyurethane adhesive characterized by containing at least a polyurethane polyol (A) synthesized from a polyol compound and a polyisocyanate compound, and an ether ester compound (B) represented by formula (1), wherein the polyurethane The polyol (A) is to provide a polyurethane pressure-sensitive adhesive containing 46 parts by mass or more and 100 parts by mass or less of a polyether polyol compound in 100 parts by mass of the polyol compound as a constituent material.

The polyurethane adhesive of the present invention has the effect of suppressing the increase in adhesive strength over time. As a film, and further as a protective film for a display of consumer equipment, it is possible to protect the image quality of a display device without impairing it.

The polyurethane adhesive according to the present invention will be specifically described below.

It is preferable to add a polyether polyol compound to the polyol compound, which is a constituent material of the polyurethane polyol (A). In addition, polyols such as polyester polyol compounds, liquid rubber polyol compounds, and polyol monomers, that is, compounds containing a plurality of hydroxyl groups, are added. can be used.
The amount of the polyether polyol compound added is 46 parts by mass or more and 100 parts by mass or less in a total of 100 parts by mass of the polyol compound.

Examples of polyether polyol compounds include polyethylene glycol, polypropylene glycol, polytetramethylene ether polyol, etc. obtained by polymerization of ethylene oxide, propylene oxide, tetrahydrofuran, 1,4-butanediol, etc., and copolymers thereof. These can be used in combination.

A commercially available polyether polyol compound can be used. As commercially available products, from AGC, product name: 385SO, product name: 550SO, product name: 100S, from ADEKA, product name: ADEKA POLYETHER P SERIES, ADEKA POLYETHER BPX SERIES, ADEKA POLYETHER G SERIES, MITSUBISHI Chemical company sells product name: PTMG650, product name: PTMG2000, product name: PTMG3000, and Covestro company sells product name: ARCOL POLYOL 5613, product name: ARCOL POLYOL 5603, product name: ARCOL POLYOL 1032, and the like.

Polyester polyol compounds, which are polyol compounds other than polyether polyol compounds, are available from Kuraray Co., Ltd., product name: Kuraray Polyol P-1010, product name: Kuraray Polyol P-2010, product name: Kuraray Polyol P-3010, product name: Kuraray. Polyol P-5010 and the like are on the market. The liquid rubber polyol compound is sold by Nippon Soda Co., Ltd. under the product name: G-1000, product name: G-3000, product name: GI-1000, product name: GI-3000, and the like. Examples of polyol monomers include polyol compounds having 2 to 30 carbon atoms such as 1,2-ethanediol and 1,3-propanediol.

Examples of polyisocyanate compounds used in producing polyurethane polyol (A) include hexamethylene diisocyanate (HDI), diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), isophorone diisocyanate (IPDI), xylylene diisocyanate (XDI), etc. Any polyisocyanate compound can be used.

Any of monomer type, biuret type, isocyanurate type, adduct type and the like can be used as the polyisocyanate compound. Monomer-type HDI can be mentioned as a more suitable material.
Monomer-type HDI is sold by Tosoh Corporation, Asahi Kasei Corporation, Wanhua Chemical Company, etc., and any of them can be used.
One type of polyisocyanate compound may be used, or two or more types may be used in combination.

A curing catalyst can be used when the polyol compound and the polyisocyanate compound are reacted to obtain the polyurethane polyol (A). Curing catalysts such as tin 2-ethylhexanoate, tin neodecanoate, tin stearate, dibutyltin dioctoate, dibutyltin dioleyl maleate, tin dimethylbis(neodecanoate), zinc 2-ethylhexanoate, zinc neodecane, Bismuth 2-ethylhexanoate, bismuth neodecane, triethylamine, diazabicycloundecene and the like can be used. Among these curing catalysts, for example, tin dimethylbis(neodecanoate) is commercially available, and is sold under the product name: DX660 by Quzhou Jianhua Dongxu Chemical Company.

The quantitative relationship between the polyol compound, the polyisocyanate compound, and the curing catalyst is such that the curing catalyst is 0.005 to 0.5 parts by mass, more preferably 0.01 to 100 parts by mass in total of the polyol compound and the polyisocyanate compound. It is 0.1 part by mass.

When obtaining polyurethane polyol (A) using a polyol compound, a polyisocyanate compound and a curing catalyst, a solvent can be used in order to suppress the reaction temperature rise and to adjust the viscosity.
Solvents that can be used include methyl acetate, ethyl acetate, butyl acetate, benzene, toluene, xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, n-hexane, isopropyl alcohol, propylene glycol monomethyl ether, propylene glycol dimethyl ether, and propylene glycol monomethyl. Solvents such as ether acetate and propylene carbonate are included. However, solvents other than these may be used without any problem, and two or more solvents may be used in combination.
The amount of the solvent to be used is 10 to 150 parts by mass, more preferably 15 to 70 parts by mass, per 100 parts by mass of the solid content of the polyurethane polyol (A).

As a method for synthesizing the polyurethane polyol (A), a polyol compound, a polyisocyanate compound, a curing catalyst and a solvent are weighed into a separable flask, equipped with a stirring blade and a lid, and rotated at a speed of 10 to 500 rpm, more preferably 50. It can be obtained by stirring at ~200 rpm, a temperature of 50 to 100°C, more preferably 60 to 90°C, and a time of 10 to 120 minutes, more preferably 30 to 90 minutes.

When obtaining the adhesive, a liquid obtained by blending the ether ester compound (B) represented by the formula (1) with the polyurethane polyol (A) and a polyisocyanate compound as a curing agent is coated on a film such as a PET film in a solvent. Coat so that the thickness after volatilization and reaction is 5 to 200 μm, more preferably 10 to 100 μm, at a temperature of 80 to 200° C., more preferably 100 to 150° C., for a time of 0.5 to After solvent volatilization and primary curing for 20 minutes, more preferably 1 to 5 minutes, the temperature is 25 to 70 ° C., more preferably 30 to 60 ° C., the time is 24 to 120 hours, more preferably It can be obtained by curing and secondary hardening for 48 to 96 hours.

The ether ester compound (B) represented by the formula (1) is a compound containing an ether group and having at least one hydroxyl group, and a carboxyl group at both ends of a dicarboxylic acid compound having 1 to 8 carbon atoms in a methylene group. It is a compound obtained by subjecting a group to an esterification reaction.
A commercially available product can be used as the ether ester compound (B). As commercial products, Geo-Young Co., Ltd. sells the product name: GYFLEX-95, and Adeka Co., Ltd. sells the product name: RS-107.
The amount of the ether ester compound (B) represented by the formula (1) is 1.5 parts by mass or more and 49.5 parts by mass or less, more preferably 5 parts by mass, per 100 parts by mass of the solid content of the polyurethane polyol (A). ~45 parts by mass.

Any of the polyisocyanate compounds described above can be used as the polyisocyanate compound that is the curing agent. Of the monomer type, biuret type, isocyanurate type, and adduct type, the isocyanurate type is more preferred, and hexamethylene diisocyanate (HDI) is more preferred. As the isocyanurate-type HDI, Tosoh Corporation sells products such as product name: Coronate HX, product name: Coronate HXR, and product name: Coronate HK.
The amount added is 1 to 25 parts by mass, more preferably 10 to 20 parts by mass, per 100 parts by mass of the solid content of the polyurethane polyol (A).

Various additives can be added to the polyurethane adhesive of the present application as required. Additives include antioxidants, reaction modifiers, plasticizers, antiblocking agents, silane coupling agents, dispersants, dyes, pigments, inorganic and organic fillers, flame retardants, UV absorbers, light stabilizers, and electrical insulation. Improvement agents, lubricants, antifungal agents, anti-hydrolysis agents, abrasives and the like can be mentioned.

A commercially available antioxidant can be used. As commercial products, BASF Corporation sells product name: Irganox 1010, product name: Irganox 1520L, product name: Irganox 1135, and the like.
The amount added is, per 100 parts by mass of the solid content of the polyurethane polyol (A),
0.01 to 30 parts by mass, more preferably 0.5 to 5 parts by mass.

Acetylacetone can be added to the polyurethane adhesive of the present application in order to adjust the pot life.

Next, the polyurethane pressure-sensitive adhesive of the present invention will be described in detail with reference to examples and comparative examples.

<Synthesis of polyurethane polyol (A1)>
In a separable flask, 42.8 g of ARCOL POLYOL 5613, 32.0 g of ARCOL POLYOL 1032, 21.3 g of PTMG2000, 3.9 g of Tosoh's monomer type HDI, 0.03 g of curing catalyst DX660, and ethyl acetate. 22.22 g was weighed out, a stirring blade and a lid were attached, the rotation speed was 100 rpm, the reaction temperature was 75° C., and the stirring time was 60 minutes to synthesize polyurethane polyol (A1).
When the total of the polyol compounds is converted to 100 parts by mass, the polyether polyol compound is 100 parts by mass.

<Preparation of Polyurethane Adhesive Coating Liquid of Example 1>
122.3 g of the polyurethane polyol (A1) solution obtained in the synthesis of polyurethane polyol (A1), 10.0 g of GYFLEX-95 and 1.0 g of Irganox 1010 were weighed into a container and stirred until uniform. 15 g of Coronate HX was added to this liquid, and the mixture was stirred until uniform, to obtain a polyurethane adhesive coating liquid of Example 1.

<Synthesis of polyurethane polyol (A2)>
In a separable flask, 42.8 g of ARCOL POLYOL 5613, 13.0 g of ARCOL POLYOL 1032, 21.3 g of PTMG2000, 19.0 g of Kuraray Polyol P-3010, 3.9 g of Tosoh's monomer type HDI, a curing catalyst Weigh 0.03 g of DX660 and 22.22 g of ethyl acetate, attach a stirring blade and a lid, rotate at 100 rpm, reaction temperature at 75 ° C., and stir for 60 minutes to synthesize polyurethane polyol (A2). bottom. When the total of polyol compounds is converted to 100 parts by mass, the polyether polyol compound is 80.2 parts by mass.
Kuraray Polyol P-3010 is a polyester polyol compound obtained by dehydration condensation of 3-methyl-1,5-pentanediol and adipic acid.

<Synthesis of polyurethane polyol (A3)>
In a separable flask, 42.8 g of ARCOL POLYOL 5613, 5.3 g of PTMG2000, 48.0 g of Kuraray Polyol P-3010, 3.9 g of Tosoh's monomer type HDI, 0.03 g of curing catalyst DX660, acetic acid 22.22 g of ethyl was weighed out, a stirring blade and a lid were attached, the rotation speed was 100 rpm, the reaction temperature was 75° C., and the stirring time was 60 minutes to synthesize polyurethane polyol (A3).
When the total of the polyol compounds is converted to 100 parts by mass, the polyether polyol compound is 50.1 parts by mass.

<Synthesis of Polyurethane Polyol (A′)>
In a separable flask, 42.8 g of ARCOL POLYOL 5613, 53.3 g of Kuraray Polyol P-3010, 3.9 g of Tosoh's monomer type HDI, 0.03 g of curing catalyst DX660, and 22.22 g of ethyl acetate were weighed. A stirring blade and a lid were attached, the number of revolutions was 100 rpm, the reaction temperature was 75° C., and the stirring time was 60 minutes to synthesize polyurethane polyol (A′). When the total of the polyol compounds is converted to 100 parts by mass, the polyether polyol compound is 44.5 parts by mass.

<Preparation of Polyurethane Adhesive Coating Liquids of Examples 2 to 7 and Comparative Examples 1 to 7>
Polyurethane adhesive coating liquids of Examples 2 to 7 and Comparative Examples 1 to 7 were prepared in the same manner as in the preparation of the polyurethane adhesive coating liquid of Example 1, using the proportions of various materials shown in Tables 1 and 2. made. In both cases, the added amount of Coronate HX was 15 g.
RS-735 and W-262 are compounds obtained by reacting hydroxyl groups at both ends of a glycol-based diol compound with two carboxylic acid-containing compounds, and GYFLEX-N is diisobutyl adipate.

<Curability confirmation>
The polyurethane adhesive coating liquids of Examples 1 to 7 and Comparative Examples 1 to 7 were applied onto a PET film having a thickness of 75 μm so that the thickness after drying and reaction would be 75 μm, followed by heating at 120°C for 3 minutes. dried and reacted. After drying and reacting, a PET film (hereinafter referred to as a separator) with a thickness of 50 μm that has been surface-coated with silicone or fluororesin and treated for easy release (hereinafter referred to as a separator) is attached to the coated film, and then the separator is peeled off. It was visually confirmed whether or not there was migration of the adhesive component. When there was no transfer of the adhesive component to the separator side, it was evaluated as pass (: ○), and when there was transfer of the adhesive component to the separator side, it was evaluated as failed (: x).

<Initial adhesive strength test>
In the same manner as in the confirmation of curability, the thickness of the polyurethane adhesive after drying and reaction was made to be 75 μm, a separator was attached, and cured at 40° C. for 3 days, separator/polyurethane adhesive/PET. A specimen of the film was made.
This test piece was cut into strips with a width of 25 mm, the separators were peeled off, and the strips were pasted on a glass base material and pressed under a load of 2 kg to prepare a test piece for adhesive force measurement.
A 180° peel test was performed at a measurement temperature of 23°C and a pulling speed of 300 mm/min to measure the initial adhesive strength. Judgment criteria are that 10 mN/25 mm or more and 30 mN/25 mm or less are acceptable, and less than 10 mN/25 mm and greater than 30 mN/25 mm are unacceptable.

<Adhesive force increase test>
After bonding the test piece prepared in the initial adhesive force test to the glass substrate, it was stored in an environment of 80° C. for 7 days and subjected to a heat resistance test. A 180° peel test was performed at a measurement temperature of 23°C and a pulling speed of 300 mm/min. Criteria for judgment are that the rate of increase in adhesive strength after the heat resistance test from the initial adhesive strength is less than 120%, and is unacceptable if it is 120% or more.

<Confirmation of adhesive residue>
After bonding the test piece prepared in the initial adhesive strength test to the glass base material, it was stored in an environment of 60° C. and 90% RH for 7 days, and subjected to a moisture and heat resistance test. The test piece was peeled off from the glass substrate, and it was visually confirmed whether or not the adhesive component had migrated to the glass substrate side. When there was no transfer of the adhesive component to the glass substrate side, it was evaluated as pass (: ○), and when there was transfer of the adhesive component to the glass substrate side, it was evaluated as failed (: ×).

A polyurethane adhesive characterized by containing at least a polyurethane polyol (A) synthesized from a polyol compound and a polyisocyanate compound, and an ether ester compound (B) represented by formula (1), wherein the polyurethane Polyol (A) is a polyurethane adhesive containing 46 parts by mass or more and 100 parts by mass or less of a polyether polyol compound in 100 parts by mass of the polyol compound as a constituent material. , the initial adhesive strength test, the adhesive strength increase test, and the confirmation of the adhesive residue property were all passed.

Comparative Example 1, in which the ether ester compound (B) represented by formula (1) was not added, failed the initial adhesive strength test and the adhesive strength increase test. Comparative Example 2, in which the amount of the ether ester compound (B) represented by formula (1) added was small, failed in the initial adhesive strength test, while Comparative Example 3, in which the amount added was too large, failed in curability. rice field.

The ether ester compound (B) represented by the formula (1), that is, the hydroxyl group of the compound containing an ether group and having at least one hydroxyl group, and the carboxy groups at both ends of the dicarboxylic acid compound having 1 to 8 carbon atoms in the methylene group Comparative Example 4 and Comparative Example 5 using a compound obtained by reacting hydroxyl groups at both ends of a glycol-based diol compound with two carboxylic acid-containing compounds instead of a compound obtained by esterifying the compound failed the adhesive strength increase test. became.

The ether ester compound (B) represented by the formula (1), that is, the hydroxyl group of the compound containing an ether group and having at least one hydroxyl group, and the carboxy groups at both ends of the dicarboxylic acid compound having 1 to 8 carbon atoms in the methylene group Comparative Example 6, which used diisobutyl adipate instead of the esterified compound, also failed the adhesive force increase test.

When the total amount of polyol compounds was converted to 100 parts by mass, Comparative Example 7 using polyurethane polyol (A') containing 44.5 parts by mass of polyether polyol compound failed the adhesive residue test.

A polyurethane polyol synthesized from a polyol compound and a polyisocyanate compound, wherein the polyurethane polyol (A) contains 46 parts by mass or more and 100 parts by mass or less of a polyether polyol compound in 100 parts by mass of the polyol compound, and an ether group. Moreover, it was shown that a compound (B) obtained by subjecting a hydroxyl group of a compound having at least one hydroxyl group to an esterification reaction between carboxy groups at both ends of a dicarboxylic acid compound having 1 to 8 carbon atoms in a methylene group (B) is essential. .

Claims (4)

a polyurethane polyol (A) synthesized from a polyol compound and a polyisocyanate compound;
an ether ester compound (B) represented by formula (1),
A polyurethane adhesive characterized by containing at least
The polyurethane polyol (A) contains, in 100 parts by mass of a polyol compound,
A polyurethane adhesive containing 46 parts by mass or more and 100 parts by mass or less of a polyether polyol compound.

Formula (1)
However, in the ether ester compound (B), n is an integer satisfying 1 ≤ n ≤ 8, and R ₁ and R ₂ are hydrocarbon groups containing at least one ether bond, which may be substituted with substituents. , R ₁ and R ₂ may be the same or different. The polyurethane according to claim 1, wherein 1.5 parts by mass or more and 49.5 parts by mass or less of the ether ester compound (B) represented by the formula (1) is added to 100 parts by mass of the solid content of the polyurethane polyol (A). Adhesive. The polyurethane according to Claim 1 or Claim 2, wherein 1 to 25 parts by mass of a polyisocyanate compound having two or more isocyanate groups in one molecule is added as a curing agent to 100 parts by mass of the solid content of the polyurethane polyol (A). Adhesive. The polyurethane pressure-sensitive adhesive according to any one of claims 1 to 4, wherein the isocyanate compound used to obtain the polyurethane polyol (A) is monomer type hexamethylene diisocyanate (HDI), and the curing agent is isocyanurate type hexamethylene diisocyanate (HDI).