JP2022138092A - Adhesive for transparent substrates - Google Patents

Abstract

To provide an adhesive having excellent transparency and bending resistance.SOLUTION: An adhesive for transparent substrates contains (A) a polyester polyol that is a product from the condensation of an aromatic dicarboxylic acid, an aliphatic dicarboxylic acid and an aliphatic diol, and (B) a polyisocyanate.SELECTED DRAWING: None

Description

The present invention relates to an adhesive for transparent substrates.

A liquid crystal display device is configured by laminating a polarizing filter, a color filter, an electrode substrate, and the like with an adhesive layer. Laminated glass, in which an adhesive layer is interposed between two sheets of glass, is used as window glass for automobiles, aircraft, buildings, and the like in order to prevent glass fragments from scattering when broken. For example, Patent Literature 1 discloses forming an adhesive layer of laminated glass using polyvinyl butyral or ethylene vinyl acetate.

Transparency is required for such an adhesive layer, but conventional materials cannot be said to have sufficient transparency. In addition, conventional adhesive layers do not have sufficient bending resistance, and when applied to a flexible display device, repeated bending of the screen may cause cracking or peeling inside the screen.

JP 2018-066976 A

An object of the present invention is to provide an adhesive that is excellent in transparency and bending resistance.

As a result of intensive studies to solve the above problems, the present inventors have found that, in an adhesive made of a polyurethane resin, by combining an aromatic dicarboxylic acid, an aliphatic dicarboxylic acid and an aliphatic diol as raw material components of a polyester polyol, , found that the transparency and bending resistance of the adhesive layer can be improved, and completed the present invention.

That is, the present invention relates to an adhesive for transparent substrates containing (A) a polyester polyol which is a condensation reaction product of an aromatic dicarboxylic acid, an aliphatic dicarboxylic acid and an aliphatic diol, and (B) a polyisocyanate.

Preferably, the transparent substrate is glass or film.

The aliphatic diol preferably has an aliphatic skeleton having 2 to 6 carbon atoms.

Preferably, said aromatic dicarboxylic acid is selected from the group consisting of o-phthalic acid, m-phthalic acid and p-phthalic acid.

The (B) polyisocyanate is preferably an adduct of an aliphatic diisocyanate having 6 or more carbon atoms and an aliphatic polyol.

The adhesive for transparent substrates preferably further contains (C) a silicone compound having a reactive hydroxyl group.

The present invention also relates to a laminate in which a first transparent base material, an adhesive layer made of the adhesive for transparent base material, and a second transparent base material are laminated in this order.

The present invention also relates to an automotive glass comprising the laminate.

The present invention also relates to a flexible display device including the laminate.

The adhesive for transparent substrates of the present invention can provide an adhesive layer with excellent transparency and flexibility.

FIG. 2 is a schematic diagram of the substrate and coating film used in Examples 8 to 13. FIG.

The adhesive for transparent substrates of the present invention is characterized by containing (A) a polyester polyol which is a condensation reaction product of an aromatic dicarboxylic acid, an aliphatic dicarboxylic acid and an aliphatic diol, and (B) a polyisocyanate. do.

<(A) polyester polyol>
The (A) polyester polyol used in the present invention is a condensation reaction product of an aromatic dicarboxylic acid, an aliphatic dicarboxylic acid and an aliphatic diol.

Aromatic dicarboxylic acids are not particularly limited, and include o-phthalic acid (orthophthalic acid), m-phthalic acid (isophthalic acid), p-phthalic acid (terephthalic acid), naphthalenedicarboxylic acid, biphenyldicarboxylic acid, and acid anhydrides thereof. and reactive derivatives such as compounds, alkyl esters, and acid halides. Among these, aromatic dicarboxylic acids having 8 to 14 carbon atoms and reactive derivatives thereof are preferable from the viewpoint of availability and cost as raw materials, and o-phthalic acid, m-phthalic acid, p-phthalic acid and Reactive derivatives thereof are particularly preferred. These dicarboxylic acids can be used alone or in combination of two or more.

The aliphatic dicarboxylic acid is not particularly limited, and includes linear, branched or cyclic aliphatic dicarboxylic acids, and reactive derivatives thereof such as acid anhydrides, alkyl esters and acid halides. Specifically, succinic acid, adipic acid, sebacic acid, glutaric acid, azelaic acid, maleic acid, fumaric acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, cyclopentanedicarboxylic acid and the like. Among these, aliphatic dicarboxylic acids having 4 to 9 carbon atoms and reactive derivatives thereof are preferable from the viewpoint of availability and cost as raw materials, and among them, linear aliphatic dicarboxylic acids and reactive derivatives thereof are preferred. More preferred are adipic acid and its reactive derivatives. These dicarboxylic acids can be used alone or in combination of two or more.

The ratio of the aromatic dicarboxylic acid to the aliphatic dicarboxylic acid is preferably 20 to 80% by weight, more preferably 30 to 70% by weight, based on the total 100 parts by weight of both. If it is less than 20% by weight, the adhesiveness to the substrate tends to decrease, and if it exceeds 80% by weight, the elasticity and flexibility of the adhesive layer tend to decrease.

The aliphatic diol is not particularly limited, and may be linear (ethylene glycol, diethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, etc.), branched (1,2-propanediol (propylene glycol), neopentyl glycol, 3-methyl-1,5-pentanediol, 2,2-diethyl-1,3-propanediol, 1,2-butanediol, 1,3 -butanediol, 2,3-butanediol, etc.) or cyclic (1,4-bis(hydroxymethyl)cyclohexane, 2,2-bis(4-hydroxycyclohexyl)propane) aliphatic diols. These diols can be used alone or in combination of two or more. Among these, those having 2 to 8 carbon atoms are preferred, and those having 2 to 6 carbon atoms are more preferred, from the viewpoint of availability as raw materials and cost.

As the diol component, an aliphatic diol and an aromatic diol may be used in combination, but the proportion of the aliphatic diol in the total diol component is preferably 60 to 100% by weight, more preferably 70 to 100% by weight. More preferably, 80 to 100% by weight is even more preferable. If it is less than 60% by weight, the elasticity and flexibility of the adhesive layer tend to decrease.

(A) The number average molecular weight (Mn) of the polyester polyol is preferably 1,000 to 30,000, more preferably 10,000 to 20,000. If it is less than 1,000, the elasticity tends to decrease, and if it exceeds 30,000, the viscosity tends to be high and the handleability tends to greatly decrease. The number average molecular weight can be determined in terms of polystyrene using gel permeation chromatography (GPC).

(A) The weight average molecular weight (Mw) of the polyester polyol is preferably 2,000 to 60,000, more preferably 20,000 to 40,000. If it is less than 2,000, the elasticity tends to decrease, and if it exceeds 60,000, the viscosity tends to be high and the handleability tends to greatly decrease. In addition, the weight average molecular weight can be determined in terms of polystyrene using GPC.

(A) The hydroxyl value of the polyester polyol is preferably 5 to 100 mgKOH/g, more preferably 5 to 50 mgKOH/g. If it is less than 5 mgKOH/g, there is a tendency for the adhesion strength to decrease due to a decrease in crosslink density, and if it exceeds 100 mgKOH/g, the water resistance of the adhesive layer tends to decrease. The hydroxyl value can be determined by esterifying a polyester polyol with a pyridine solution of phthalic anhydride and titrating excess phthalic anhydride with a sodium hydroxide solution (according to JIS K 1557-1).

(A) Polyester polyol can be obtained by dehydration condensation of an aromatic dicarboxylic acid, an aliphatic dicarboxylic acid and an aliphatic diol by a known method.

The ratio of the dicarboxylic acid component (aromatic dicarboxylic acid and aliphatic dicarboxylic acid) to the diol component is the ratio of the total number of moles of hydroxyl groups contained in the diol component to the total number of moles of carboxy groups contained in the dicarboxylic acid (hydroxyl group/carboxy group) is preferably from 0.5 to 1.5, more preferably from 0.8 to 1.2.

<(B) Polyisocyanate>
The (B) polyisocyanate used in the present invention is not particularly limited, and examples thereof include linear, branched or cyclic aliphatic polyisocyanates and aromatic polyisocyanates. Aliphatic polyisocyanates include tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and the like. Aromatic diisocyanates include toluene diisocyanate, naphthylene diisocyanate, and xylylene diisocyanate. Adducts obtained by addition reaction of these polyisocyanates with polyols such as glycerin and trimethylolpropane can also be used. These polyisocyanates can be used alone or in combination of two or more.

Among them, those having an aliphatic skeleton (aliphatic polyisocyanates and adducts of aliphatic polyisocyanates and aliphatic polyols) are preferable because they yield adhesive layers with high elasticity and high flexibility. In addition, from the viewpoint of ease of availability as a raw material and cost, an adduct of an aliphatic diisocyanate having 6 or more carbon atoms, preferably 6 to 12 carbon atoms, such as hexamethylene diisocyanate, and an aliphatic polyol is more preferable, and hexamethylene Adducts of diisocyanate and trimethylolpropane are particularly preferred.

A polyisocyanate having an aliphatic skeleton and a polyisocyanate having an aromatic skeleton may be used in combination, but the ratio of those having an aliphatic skeleton is preferably 50 to 100% by weight in the total polyisocyanate component, It is more preferably 70 to 100% by weight or more, and even more preferably 80 to 100% by weight or more. If it is less than 50% by weight, the elasticity and flexibility of the adhesive layer tend to decrease.

NCO%, which indicates the weight percentage of NCO groups in the polyisocyanate, is preferably 2 to 30%, more preferably 2 to 20%.

<(C) Silicone compound having a reactive hydroxyl group>
The adhesive for transparent substrates of the present invention preferably further contains (C) a silicone compound having a reactive hydroxyl group. A "reactive hydroxyl group" means a hydroxyl group having reactivity with an isocyanate group. Since the silicone compound acting as a slip agent has a reactive hydroxyl group, it reacts with the polyisocyanate and is fixed to the cured adhesive layer, and the flexibility of the adhesive layer can be maintained for a long period of time.

In (C) a silicone compound having a reactive hydroxyl group, the reactive hydroxyl group may or may not be directly linked to Si. Also, the reactive hydroxyl group may be one produced by hydrolysis of an alkoxysilyl group or the like. (C) The silicone compound having a reactive hydroxyl group includes, in addition to the reactive hydroxyl group, reactive groups such as (meth)acrylic, vinyl, amino and epoxy groups, alkyl groups, ester groups, aralkyl groups and phenyl groups. may have non-reactive groups such as polyether groups. Two or more of these silicone compounds may be used in combination.

(C) The number average molecular weight of the silicone compound having a reactive hydroxyl group is preferably 1,000 to 20,000, more preferably 3,000 to 15,000. If it is less than 1,000, it tends to separate from the adhesive layer and the effect does not last, and if it exceeds 20,000, it tends to be difficult to orient in the adhesive layer.

(C) The weight average molecular weight of the silicone compound having a reactive hydroxyl group is preferably 2,000 to 40,000, more preferably 6,000 to 30,000. If it is less than 2,000, it tends to separate from the film and the effect does not last, and if it exceeds 40,000, it tends to be difficult to orient in the adhesive layer.

(C) The hydroxyl value of the silicone compound having a reactive hydroxyl group is preferably 30-200 mgKOH/g, more preferably 80-150 mgKOH/g. If it is less than 30 mgKOH/g, it tends to be released from the membrane and the effect does not last, and if it exceeds 200 mgKOH/g, the water solubility increases and it tends to be released from the membrane by moisture.

<Other additives>
Various additives such as dispersants, solvents, leveling agents, curing catalysts, thickeners, ultraviolet absorbers, light stabilizers, antioxidants, and silane coupling agents may be added to the adhesive for transparent substrates of the present invention, if necessary. Additives can be added.

The dispersant is not particularly limited, and examples thereof include polycarboxylic acid-based dispersants and polyamine-based dispersants. Although the amount to be added is not particularly limited, for example, 0.1 to 10 parts by weight can be added to 100 parts by weight of polyester polyol (A).

Solvents are not particularly limited, and include cyclohexanone, butyl acetate, ethyl acetate, xylene, toluene, methyl isobutyl ketone, methyl ethyl ketone and the like. These solvents can be used alone or in combination of two or more. The content of the solvent in the adhesive for transparent substrates is not particularly limited, and may be adjusted as necessary.

The leveling agent is not particularly limited, and examples thereof include polyether leveling agents, fluorine leveling agents, polyester leveling agents, siloxane leveling agents, silicone leveling agents, and acrylic leveling agents. The amount of the leveling agent to be blended is not particularly limited, but is preferably 0.1 to 10 parts by weight, more preferably 0.2 to 5 parts by weight, per 100 parts by weight of the polyester polyol (A).

The silane coupling agent is not particularly limited, and includes vinyl silane coupling agents such as vinyltrimethoxysilane and vinyltriethoxysilane, (meth)acrylic silane coupling agents such as γ-methacryloxypropyltrimethoxysilane, 2- Epoxy silane coupling agents such as (3,4-epoxycyclohexyl)ethyltrimethoxysilane, and amine silane coupling agents such as γ-aminopropyltrimethoxysilane and γ-aminopropyltriethoxysilane are included. Although the amount of the silane coupling agent to be added is not particularly limited, it is preferably 0.1 to 10 parts by weight, more preferably 0.2 to 5 parts by weight, per 100 parts by weight of the polyester polyol (A).

<Adhesive for transparent substrate>
The form of the adhesive for transparent substrates of the present invention may be either one-component type or two-component type, but the two-component type is preferred from the viewpoint of ensuring the toughness of the film.

The blending ratio of the components is the ratio of the total number of moles of isocyanate groups contained in (B) polyisocyanate to the total number of moles of hydroxyl groups contained in (A) polyester polyol and (C) a silicone compound having a reactive hydroxyl group (isocyanate group / hydroxyl group) is preferably 0.7 to 1.5, more preferably 0.8 to 1.2.

(C) The amount of the silicone compound having a reactive hydroxyl group is preferably 0.3 to 25 parts by weight, more preferably 0.3 to 10 parts by weight, more preferably 0.5 to 0.5 parts by weight, based on 100 parts by weight of the polyester polyol (A). 5 parts by weight is more preferred. If it is less than 0.3 parts by weight, the flexibility of the adhesive layer may be insufficient, and if it exceeds 25 parts by weight, the water resistance may be lowered.

<Laminate>
The laminate of the present invention is formed by laminating a first transparent substrate, an adhesive layer made of the adhesive for transparent substrates, and a second transparent substrate in this order.

The material of the transparent substrate is not particularly limited, and examples thereof include resin, rubber, and glass. Examples of resins include electrostatically processed polypropylene, polycarbonate resin, nylon 6, polyethylene terephthalate resin, acrylic resin, polyurethane resin, polyester resin, ABS resin, hard vinyl chloride, soft vinyl chloride, vinyl acetate resin, polystyrene, and the like. Examples of rubber include butyl rubber, urethane rubber, silicone rubber, and the like. Examples of glass include heat-absorbing glass, heat-reflecting glass, green glass, lined plate glass, and colored glass. The transparent substrate may be a composite material in which two or more of these materials are combined. The shape of the substrate is also not particularly limited, and examples thereof include a flat surface, a curved surface, a spherical surface, and the like. Also, the first transparent substrate and the second transparent substrate may be the same or different.

The method of forming the adhesive layer is not particularly limited, and for example, a method of applying an adhesive for a transparent substrate onto the first substrate, bonding the second substrate onto the coating layer, and then curing. is mentioned. Coating methods include brush, roller, bar coating, spin coating, dipping, spraying, printing, inkjet and the like. The curing method is also not particularly limited, and known methods such as curing by drying at room temperature and accelerated curing by heating can be used. If necessary, the adhesive layer may be cured while being degassed by a vacuum degassing method, a nip roll method, or the like. When heating, the temperature is preferably 30 to 150°C, more preferably 50 to 100°C.

The thickness of the adhesive layer is not particularly limited, and is preferably 5 to 2000 μm. If the thickness is less than 5 μm, the adhesive layer may be easily broken due to insufficient strength, and if it exceeds 2000 μm, the reactivity tends to be uneven. In particular, when applied to automotive glass, the thickness of the adhesive layer is preferably 300 to 2000 μm, more preferably 400 to 1000 μm. Since the adhesive layer obtained in the present invention has high transparency, the transparency of the entire laminate can be ensured even if the thickness of the adhesive layer is large. When applied to a flexible display device, the thickness of the adhesive layer is preferably 5-400 μm, more preferably 10-200 μm. If a thickness exceeding 100 μm is required, the coating may be applied in several steps, and finally the second transparent substrate may be adhered and cured.

When the adhesive layer has a thickness of 50 μm, it preferably exhibits an elongation of 300% or more, more preferably 350% or more. Here, the elongation rate is a value obtained by a tensile test of a free film.

The laminate of the present invention preferably has a total light transmittance of 75% or more, more preferably 80% or more, still more preferably 90% or more, and particularly preferably 95% or more. .
The total light transmittance of the adhesive layer alone is preferably 90% or more, more preferably 93% or more, and even more preferably 95% or more. The total light transmittance can be evaluated by the total light transmittance test of JIS K 7375 using a visible light transmittance measuring instrument.

The laminate of the present invention preferably has a haze of 5% or less, more preferably 2% or less. Also, the haze of the adhesive layer alone is preferably 1% or less, more preferably 0.5% or less. Haze can be measured and calculated with a visible light transmittance meter.

The refractive index of the adhesive layer can be appropriately set according to the use of the laminate, and can be, for example, 1.2 to 1.7 at a wavelength of 550 nm.

The laminate of the present invention preferably has excellent flexibility. The flexibility can be evaluated by the flexibility test of JIS K 5600-5-1. The laminate of the present invention uses a test apparatus of 3.1.2 Type 1 in Part 5 of the JIS: Mechanical properties of coating film Section 1: Bend resistance (cylindrical mandrel method), It is preferable that cracks and peeling of the coating film do not occur even in a test using a mandrel with a diameter of 2 mm.

The adhesive for transparent substrates of the present invention can be used for bonding polarizing filters, color filters, electrode substrates, and the like in flexible display devices and flexible touch panels. The adhesive for transparent substrates of the present invention can also be used for laminated glass for automobiles, laminated glass for aircraft, laminated glass for ships, and laminated glass for buildings. can be used particularly preferably for

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples. Moreover, unless otherwise specified, "parts" means parts by weight.

(1) Various chemicals used in Examples and Comparative Examples Silicone compound 1: KR-500 (a silicone compound having a methoxysilyl group, containing 28% by weight of methoxy groups), manufactured by Shin-Etsu Chemical Co., Ltd. Silicone compound 2: BYK-330 (manufactured by BYK)
・ Silane coupling agent: BYK-4512 (manufactured by BYK)
・Adduct of hexamethylene diisocyanate and trimethylolpropane: Duranate E402-90T (NCO%: 8.5%) manufactured by Asahi Kasei ・Adduct of m-xylene diisocyanate and trimethylolpropane: Desmodur L75 (NCO%: 13 .3%) manufactured by Sumika Covestro Urethane Co., Ltd. Dispersant: BYK-161 (manufactured by BYK)

(2) The produced resin composition was evaluated by the following methods.
<Adhesion>
A coating film having a thickness of 15 μm was obtained by applying the resin composition to various substrates listed in Table 1 and then drying the film. After making 1 mm square cuts in the film with a cutter knife in a grid pattern, an adhesive tape was applied. Adhesion was evaluated in the following 7 stages by attaching, peeling, and observing the ratio of the film remaining on the substrate (according to JIS K 5600-5-6 crosscut test method).
6: The coating adhered to the base material, and no part was peeled off.
5: The coating film was peeled off in the range of more than 0% to 5% or less.
4: The coating film was peeled in the range of more than 5% to 15% or less.
3: The coating film was peeled off in the range of more than 15% to 35% or less.
2: The coating film was peeled in the range of more than 35% to 65% or less.
1: The coating film was peeled in a range exceeding 65%. However, when the cross-cutting was not made and only the adhesive tape was applied and peeled off, the film was not peeled off.
0: The coating film was peeled in a range exceeding 65%. In addition, it was peeled off only by sticking and peeling with an adhesive tape without making a cross-cut incision.

<Elongation rate>
The resin composition was applied to a natural rubber substrate to form a coating film having a thickness of 50 μm, and both ends of the coating film were stretched and deformed to measure the elongation rate of the coating film.
The elongation percentage (%) is expressed as a ratio of the length of the base material at the time when the coating film is broken under tension to the length before tensioning.

(3) Adhesion and elongation evaluation 1
Example 1
14 parts of terephthalic acid and 14 parts of isophthalic acid, which are aromatic dicarboxylic acids, and 30 parts of adipic acid, which is an aliphatic dicarboxylic acid, were mixed to obtain a dicarboxylic acid mixture. 8 parts of ethylene glycol, 17 parts of neopentyl glycol and 17 parts of 1,6-hexanediol, which are aliphatic diols, were mixed with this, and condensation reaction was carried out by a known method to obtain a polyester polyol (A1). (A1) had an Mn of 17400, an Mw of 34100, and a hydroxyl value (solid) of 10 mgKOH/g.
1 part of the silicone compound 1 was mixed with 100 parts of the obtained (A1), and 100 parts of cyclohexanone was further mixed as a solvent to prepare a main agent. 4 parts of an adduct of hexamethylene diisocyanate and trimethylolpropane were mixed as a curing agent to obtain a resin composition.
Table 1 shows the evaluation results of adhesion and elongation.

Example 2
A resin composition was obtained in the same manner as in Example 1, except that bisphenol A, which is an aromatic diol, was used instead of 1,6-hexanediol.
Table 1 shows the evaluation results of adhesion and elongation.

Example 3
Resin composition in the same manner as in Example 1 except that the adduct of hexamethylene diisocyanate and trimethylolpropane was not used, and 5 parts of the adduct of m-xylene diisocyanate and trimethylolpropane having an aromatic skeleton were blended instead. got stuff
Table 1 shows the evaluation results of adhesion and elongation.

Example 4
A resin composition was obtained in the same manner as in Example 1, except that silicone compound 1 was not used.
Table 1 shows the evaluation results of adhesion and elongation.

Comparative example 1
A resin composition was obtained in the same manner as in Example 1, except that 29 parts of terephthalic acid and 29 parts of isophthalic acid were used as dicarboxylic acids.
Table 1 shows the evaluation results of adhesion and elongation.

As shown in Table 1, each example in which an aromatic dicarboxylic acid, an aliphatic dicarboxylic acid, and an aliphatic diol are combined as raw material components of a polyester polyol has a higher elongation than Comparative Example 1 in which no aliphatic dicarboxylic acid is used. rate.

(4) Adhesion and elongation evaluation 2
Example 5
A dicarboxylic acid mixture containing 14 parts of terephthalic acid, 14 parts of isophthalic acid and 30 parts of adipic acid is mixed with 11 parts of neopentyl glycol, 17 parts of 1,6-hexanediol and 10 parts of propylene glycol and subjected to a condensation reaction to form a polyester. A polyol was obtained (Mn: 10000, Mw: 20000, hydroxyl value (solid): 20 mgKOH/g). This polyester polyol was mixed with 1 part of silicone compound 1 and 100 parts of cyclohexanone to prepare a main component. Here, 4 parts of an adduct of hexamethylene diisocyanate and trimethylolpropane were mixed as a curing agent to obtain a resin composition.
Table 2 shows the evaluation results of adhesion and elongation.

Example 6
A resin composition was obtained in the same manner as in Example 5, except that 2 parts of a silane coupling agent was added to the composition of Example 5.
Table 2 shows the evaluation results of adhesion and elongation.

Example 7
A resin composition was obtained in the same manner as in Example 5, except that 20 parts of the silicone compound 1 was used in the formulation of Example 5, and 0.5 parts of the silicone compound 2 and 2 parts of the silane coupling agent were added. rice field.
Table 2 shows the evaluation results of adhesion and elongation.

As shown in Table 2, Example 6 exhibited the same elongation rate and adhesion to various substrates as Example 5. Example 7 also showed similar elongation to Example 5 and adhesion to various substrates.

(5) Evaluation of Elasticity and Transparency of Resin Composition Single Film Example 8
The resin composition of Example 1 was applied to a 0.1 mm-thick acrylic resin substrate and then dried to obtain a 15 μm-thick coating film. A schematic diagram of the base material and the coating film is shown in FIG. The modulus, strain under load, haze, and total light transmittance of this coating film were measured using a texture analyzer TA. It was measured using XTplus (Eiko Seiki). Table 3 shows the evaluation results.

Example 9
The resin composition of Example 2 was applied to a 0.1 mm-thick acrylic resin substrate and then dried to obtain a 15 μm-thick coating film. This coating film was evaluated in the same manner as in Example 8. Table 3 shows the results.

Example 10
The resin composition of Example 3 was applied to a 0.1 mm-thick acrylic resin substrate and then dried to obtain a 15 μm-thick coating film. This coating film was evaluated in the same manner as in Example 8. Table 3 shows the results.

Example 11
The resin composition of Example 4 was applied to a 0.1 mm-thick acrylic resin base material and then dried to obtain a 15 μm-thick coating film. This coating film was evaluated in the same manner as in Example 8. Table 3 shows the results.

Example 12
The resin composition of Example 6 was applied to a 0.1 mm-thick acrylic resin substrate and then dried to obtain a 15 μm-thick coating film. This coating film was evaluated in the same manner as in Example 8. Table 3 shows the results.

Example 13
The resin composition of Example 7 was applied to a 0.1 mm-thick acrylic resin substrate and then dried to obtain a 15 μm-thick coating film. This coating film was evaluated in the same manner as in Example 8. Table 3 shows the results.

As shown in Table 3, the adhesive layers composed of the compositions of Examples 1 to 4 and 6 to 7 exhibited a low haze value of 0.5% or less and a high total light transmittance of 93% or more.

(6) Transparency Evaluation Example 14 on Glass Substrate
The resin composition of Example 1 was formed into a film by spin coating on a non-alkali glass substrate (EagleXE, Corning). After forming the film, it was dried to obtain a coating film having a thickness of 15 μm. The total light transmittance, haze, YI (yellow index), n (refractive index) at a wavelength of 550 nm, and k (extinction coefficient) of the laminate including this coating film and substrate were measured using an ellipsometer. Table 4 shows the evaluation results.

Examples 15-17
The resin compositions of Examples 4, 6, and 7 were formed into films by spin coating on alkali-free glass substrates (EagleXE, Corning Inc.). After forming the film, it was dried to obtain a coating film having a thickness of 15 μm. The laminate including this coating film and substrate was evaluated in the same manner as in Example 14. Table 4 shows the results.

Comparative example 2
The total light transmittance, haze, YI (yellow index), n (refractive index) at a wavelength of 550 nm, and k (extinction coefficient) of the alkali-free glass substrate (EagleXE, Corning) itself used in Examples 14 to 17 were Measured using an ellipsometer. Table 4 shows the evaluation results.

As shown in Table 4, the resin compositions of Examples 1, 4, 6 and 7 showed high total light transmittance and low haze values even when coated on glass substrates. In addition, the yellow index (Y.I.) value, refractive index, and extinction coefficient, which are important performances in a laminate using glass as a substrate, showed sufficient values.

(7) Flexibility Evaluation Each of the resin compositions of Examples 1, 4, 6, and 7 was applied to a metal substrate having a thickness of 0.3 mm and then dried to form a coating film having a thickness of 15 μm on the substrate. A laminate having The flexibility of this laminate was evaluated by a flexibility test according to JIS K 5600-5-1. As a result, each laminate made of the resin compositions of Examples 1, 4, 6, and 7 was evaluated according to Part 5 of the JIS: Mechanical properties of coating film Section 1: Flex resistance (cylindrical mandrel method) 3.1.2 Using a test apparatus of type 1, even in a test using a mandrel with a diameter of 2 mm, cracking and peeling of the coating film did not occur.

Claims (9)

(A) a polyester polyol which is a condensation reaction product of an aromatic dicarboxylic acid, an aliphatic dicarboxylic acid and an aliphatic diol, and
(B) An adhesive for transparent substrates containing polyisocyanate. The transparent substrate is glass or film,
The adhesive for transparent substrates according to claim 1 . 3. The adhesive for transparent substrates according to claim 1, wherein the aliphatic diol has an aliphatic skeleton having 2 to 6 carbon atoms. The adhesive for transparent substrates according to any one of claims 1 to 3, wherein the aromatic dicarboxylic acid is selected from the group consisting of o-phthalic acid, m-phthalic acid and p-phthalic acid. . The adhesive for transparent substrates according to any one of claims 1 to 4, wherein the (B) polyisocyanate is an adduct of an aliphatic diisocyanate having 6 or more carbon atoms and an aliphatic polyol. 6. The adhesive for transparent substrates according to claim 1, further comprising (C) a silicone compound having a reactive hydroxyl group. a first transparent substrate,
An adhesive layer made of the adhesive for transparent substrates according to any one of claims 1 to 6 and a second transparent substrate,
A laminate formed by laminating in this order. An automotive glass comprising the laminate of claim 7. A flexible display device comprising the laminate of claim 7 .

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