KR-20260064631-A - Solvent-Free Adhesives and Laminates

KR20260064631AKR 20260064631 AKR20260064631 AKR 20260064631AKR-20260064631-A

Abstract

[Problem] To provide a solvent-free adhesive that can rapidly increase adhesive strength and heat seal strength and suppress appearance defects of the coating film even in low-temperature and low-humidity environments. Furthermore, to provide a laminate suitable for use as a packaging material by using the said solvent-free adhesive. [Solution] A solvent-free adhesive comprising a polyol (A) and a polyisocyanate (B), characterized by satisfying all of the following (1) to (3). (1) The above polyol (A) includes a polyol (a1) with three or more functions and a molecular weight of 200 or less. (2) The polyisocyanate (B) comprises an isocyanate-terminated urethane prepolymer (B1) which is a reaction product of a polyol (b1) and an isocyanate compound (b2), and an isocyanate monomer (B2) containing 2,4'-diphenylmethane diisocyanate, and the polyol (b1) comprises at least 80 mass% of polyether polyol (b1-1) based on the total mass of the polyol (b1). (3) The polyether polyol (b1-1) comprises a difunctional polyether polyol (b1-1A) with a number average molecular weight of 500 or less, and the content of the difunctional polyether polyol (b1-1A) with a number average molecular weight of 500 or less is 15 to 50 mass% based on the total mass of the polyol (b1).

Inventors

사이토, 아스카
우치야마, 유세이

Assignees

아티엔스 가부시키가이샤
도요 모톤 리미티드

Dates

Publication Date: 20260507
Application Date: 20251030
Priority Date: 20241031

Claims (14)

A solvent-free adhesive comprising a polyol (A) and a polyisocyanate (B), characterized by satisfying all of the following (1) to (3). (1) The above polyol (A) includes a polyol (a1) with three or more functions and a molecular weight of 200 or less. (2) The polyisocyanate (B) comprises an isocyanate-terminated urethane prepolymer (B1) which is a reaction product of a polyol (b1) and an isocyanate compound (b2), and an isocyanate monomer (B2) containing 2,4'-diphenylmethane diisocyanate, and the polyol (b1) comprises at least 80 mass% of polyether polyol (b1-1) based on the total mass of the polyol (b1). (3) The polyether polyol (b1-1) comprises a difunctional polyether polyol (b1-1A) with a number average molecular weight of 500 or less, and the content of the difunctional polyether polyol (b1-1A) with a number average molecular weight of 500 or less is 15 to 50 mass% based on the total mass of the polyol (b1).
In paragraph 1, A solvent-free adhesive in which the storage modulus and loss modulus of the solvent-free adhesive after mixing the above polyol (A) and the above polyisocyanate (B) satisfy the following formula (I) within 24 hours. Equation (I): [log(storage modulus)/log(loss modulus)]≥0.9 [In the above equation (I), the storage modulus (Pa) and the loss modulus (Pa) are values measured using a viscoelastic measuring device under conditions of frequency: 5 Hz, stress: 10 Pa, measuring instrument: parallel plate (diameter 25 mm), and 40°C.]
In paragraph 1, A solvent-free adhesive comprising 5 to 40 mass% of a difunctional polyether polyol (a2-1) having a number average molecular weight of 500 or less, based on the total mass of the polyol (A).
In paragraph 1, A solvent-free adhesive having a content of 20 to 40 mass% of the number average molecular weight of 500 or less of the difunctional polyether polyol (b1-1A) based on the total mass of the polyol (b1).
In paragraph 1, A solvent-free adhesive comprising, based on the total mass of the polyol (A), 0.5 to 10 mass% of a polyol (a1) with three or more functions and a molecular weight of 200 or less.
In paragraph 1, A solvent-free adhesive having a content of 25 mass% or less of a polyol with three or more functional groups in the polyol (b1), based on the total mass of the polyol (b1).
In paragraph 1, The above polyisocyanate (B) is a solvent-free adhesive having a urethane bond concentration of 100 to 140 mmol/g.
In paragraph 1, A solvent-free adhesive comprising 30 to 90 mass% of polyester polyol (a3) based on the total mass of the polyol (A).
In paragraph 1, A solvent-free adhesive comprising, in addition, 1 to 15 mass% of polymeric MDI based on the total mass of the polyisocyanate (B).
In paragraph 1, A solvent-free adhesive having a content of 30 to 80 mass% of the isocyanate-terminated urethane prepolymer (B1) based on the total mass of the polyisocyanate (B).
In paragraph 1, A solvent-free adhesive having a content of 15 to 70 mass% of the 2,4'-diphenylmethane diisocyanate based on the total mass of the isocyanate monomer (B2).
In paragraph 1, A solvent-free adhesive having a number average molecular weight of 800 to 2000 of the isocyanate-terminated urethane prepolymer (B1).
A laminate having at least a first substrate and a second substrate, wherein an adhesive layer formed using a solvent-free adhesive described in any one of claims 1 to 12 is interposed.
In Paragraph 13, A laminate in which the first substrate and the second substrate are each independently formed using at least one type selected from the group consisting of plastic, metal, and inorganic materials other than metal.

Description

Solvent-Free Adhesives and Laminates Embodiments of the present invention relate to a solvent-free adhesive and a laminate using said solvent-free adhesive. More specifically, the invention relates to a solvent-free adhesive suitable for forming a laminate of a plastic film and/or a deposited film, and a laminate useful as a packaging material for food, medical products, cosmetics, etc. Recently, due to stricter legal regulations and increased consideration for environmental protection and safety, there is a growing demand for solvent-free adhesives used to form laminates for packaging materials. Solvent-free adhesives (hereinafter referred to as solvent-free adhesives) are generally formulated using low molecular weight resin components for the sake of handling properties. Consequently, compared to solvent-based adhesives, solvent-free adhesives tend to exhibit slower development of adhesive performance (i.e., slower increase in adhesive strength and heat seal strength due to the cohesive force of the resin components), and thus improvements are desired. Meanwhile, as there is a demand for environmentally compliant products accompanying global movements to reduce greenhouse gas emissions, there is also a demand for biomass adhesives utilizing biomass-derived raw materials. Regarding such a situation, for example, Patent Document 1 discloses a solvent-free adhesive comprising a polyol (A) and a polyisocyanate (B) and satisfying the following (1) and (2). (1) The polyol (A) contains a polyester polyol (a1), and the content of the polyester polyol (a1) is 30 mass% or more and 70 mass% or less based on the total mass of the polyol (A). (2) The polyol (A) contains castor oil or a castor oil derivative (a2), and the content of the castor oil or a castor oil derivative (a2) is 30 mass% or more and 70 mass% or less based on the total mass of the polyol (A). Patent Document 1 makes it clear that, by the above composition, it is possible to realize a solvent-free adhesive with a rapid increase in adhesive strength and heat seal strength even in a low humidity environment, good pot life, and excellent handling properties, and in the examples, various evaluations are performed on a laminate aged in a low humidity environment of 40°C and 20%RH. <1> Solvent-free adhesive One embodiment of the present invention relates to a solvent-free adhesive. The solvent-free adhesive of the present embodiment comprises a polyol (A) and a polyisocyanate (B) and is characterized by satisfying all of the following (1) to (3). (1) The above polyol (A) includes a polyol (a1) with three or more functions and a molecular weight of 200 or less. (2) The polyisocyanate (B) comprises an isocyanate-terminated urethane prepolymer (B1) which is a reaction product of a polyol (b1) and an isocyanate compound (b2), and an isocyanate monomer (B2) containing 2,4’-diphenylmethane diisocyanate, and the polyol (b1) comprises at least 80 mass% of polyether polyol (b1-1) based on the total mass of the polyol (b1). (3) The polyether polyol (b1-1) comprises a difunctional polyether polyol (b1-1A) with a number average molecular weight of 500 or less, and the content of the difunctional polyether polyol (b1-1A) with a number average molecular weight of 500 or less is 15 to 50 mass% based on the total mass of the polyol (b1). According to the solvent-free adhesive of the present embodiment, as described in (1) to (3) above, various required properties can be easily obtained by combining a specific polyol (A) and a specific polyisocyanate (B). The solvent-free adhesive according to the present embodiment is composed of a two-component adhesive. The polyol (A) that is the first component includes a polyol (a1) with three or more functions and a molecular weight of 200 or less. Meanwhile, the polyisocyanate (B) serving as the second component comprises a reaction product of a polyol (b1) containing a specific amount of a specific polyether polyol (b1-1A) and an isocyanate compound (b2). The reaction product is a prepolymer having isocyanate groups at the terminals and containing urethane bonds formed by the reaction of (b1) and (b2). Hereinafter, the reaction product is referred to as "urethane bond-containing polyisocyanate," "isocyanate group-terminated urethane prepolymer," or "urethane prepolymer." The polyisocyanate (B) further comprises an isocyanate monomer containing 2,4’-diphenylmethane diisocyanate. The solvent-free adhesive of the present embodiment undergoes a curing reaction by mixing the polyol (A) and the polyisocyanate (B) upon use, and exhibits adhesive performance early even in low-temperature and low-humidity environments. The mechanism by which these effects are obtained is not bound by theory, but is presumed as follows. First, generally, it is believed that if an appropriate amount of moisture is present in the usage environment, the moisture plays an auxiliary role in promoting the curing reaction. Specifically, it can be inferred that mois