TWI828242B - Moisture hardening polyurethane hot melt adhesive - Google Patents

Abstract

The present invention is a moisture-hardening polyurethane hot-melt adhesive, which contains an urethane prepolymer. The urethane prepolymer is composed of a polyisocyanate component containing at least an aliphatic diisocyanate modified body and a polyol component. obtained, and has an isocyanate group at its end, the average number of functional groups of the isocyanate group in the above-mentioned polyisocyanate component is 2.0 to 3.0, and the above-mentioned polyol component contains 1 to 8 mass % of polyfunctional polyfunctional polyols with 3 or more functions. alcohol.

Description

Moisture hardening polyurethane hot melt adhesive

The invention relates to a moisture-hardening polyurethane hot-melt adhesive.

Moisture-hardening polyurethane hot-melt adhesive is a solvent-free adhesive that is solid at room temperature. The coating agent is melted by heating and applied to the base material. After being bonded to other base materials, it is cured by moisture. Since it does not use solvents, it is an environmentally friendly adhesive. However, the non-yellowing polyurethane hot-melt resin with light resistance has the problem of generating odor due to the isocyanate remaining in the raw material of the adhesive.

In order to solve this problem, Patent Document 1 discloses a solvent-free moisture-curing adhesive that improves storage stability or performance by using an allophanate group-containing polyisocyanate produced by a specific production method. It has good weather resistance, especially when receiving work, and has less odor.

In addition, Patent Document 2 discloses a one-component hardening solvent-free adhesive containing at least one polyisocyanate component selected from the group consisting of aliphatic polyisocyanates, aromatic aliphatic polyisocyanates, and derivatives thereof. ; and titanium oxide.

Furthermore, Patent Document 3 discloses a method for producing a moisture-curable polyurethane prepolymer that reduces the residual monomer content and suppresses foaming of the cured product.

[Prior technical literature] [Patent Document]

[Patent Document 1] Japanese Patent Application Publication No. 2003-201460

[Patent Document 2] Japanese Patent Application Laid-Open No. 2009-280735

[Patent Document 3] Japanese Patent No. 5853295

However, in Patent Document 1, the thermal creep resistance is insufficient, mainly due to insufficient performance as an adhesive for synthetic artificial leather. In this way, if there is a lack of heat resistance and creep resistance, for example, when processing shoes, it is necessary to attach the soles and uppers under the conditions of 150~160°C with a load of 3kg, and when processing clothing, it is necessary to attach them at 160~170°C. Under such conditions, seam tape is used for bonding, so there is a problem that the synthetic leather is easy to fall off.

Furthermore, in Patent Document 2, the elongation at break tends to be relatively small. When used as an adhesive for synthetic artificial leather, the texture of the leather is not to mention poor in cold-resistant bending and softness.

Furthermore, in Patent Document 3, there is not only a problem of heat creep resistance, but also a problem of low processability (for example, initial curability).

Therefore, an object of the present invention is to provide a moisture-curable polyurethane hot-melt adhesive which is excellent in light resistance and produces less odor during operation, and has heat creep resistance, processability, It has excellent stability over time and bonding strength, and when used for synthetic artificial leather, the texture and softness of the leather are excellent.

The above-mentioned subject is achieved by the present invention described below. That is, the present invention is as follows.

[1] A moisture-hardening polyurethane hot-melt adhesive containing an urethane prepolymer formed by the reaction of a polyisocyanate component containing at least an aliphatic diisocyanate modified body and a polyol component obtained, and has an isocyanate group at its end, the average number of functional groups of the isocyanate group in the above-mentioned polyisocyanate component is 2.0 to 3.0, and the above-mentioned polyol component contains 1 to 8 mass % of trifunctional or higher polyfunctional polyols. alcohol.

[2] The moisture-hardening polyurethane hot-melt adhesive described in [1] has a gel fraction of 85% or more.

[3] The moisture-curable polyurethane hot-melt adhesive according to [1] or [2], wherein the aliphatic diisocyanate modified body contains an allophanate-type diisocyanate.

[4] The moisture-curable polyurethane hot-melt adhesive according to any one of [1] to [3], wherein the aliphatic diisocyanate modified body contains a diisocyanate adduct of a diol.

[5] The moisture-curable polyurethane hot-melt adhesive according to any one of [1] to [4], wherein the aliphatic diisocyanate modified body contains a urea-type polyisocyanate.

[6] The moisture-curable polyurethane hot-melt adhesive according to [5], wherein the polyisocyanate component contains 10 to 37 mol% of the urea-type polyisocyanate.

[7] The moisture-curable polyurethane hot-melt adhesive according to any one of [1] to [6], which has a thermal softening point after curing of 175°C or higher.

[8] The moisture-curable polyurethane hot-melt adhesive according to any one of [1] to [7], which The elongation at break at 25°C after hardening is 300~1,000%.

[9] The moisture-curable polyurethane hot-melt adhesive according to any one of [1] to [8], further containing an isocyanate cross-linking agent.

[10] The moisture-curable polyurethane hot-melt adhesive according to [9], wherein the isocyanate cross-linking agent is an aliphatic diisocyanate modified body.

According to the present invention, it is possible to provide a moisture-curable polyurethane hot-melt adhesive which is excellent in light resistance and produces less odor during operation, and which has heat creep resistance, processability (initial curability), and stability over time. It has excellent properties and adhesion strength, especially when used for synthetic artificial leather, and the texture and softness of the leather are excellent.

10: Film for evaluation

12: Fixture

14: plumb

16:Sample

20:Gill aging thermostat

22:Turntable

FIG. 1 is a schematic explanatory diagram illustrating the form of samples used for evaluation in Examples.

FIG. 2 is an explanatory diagram illustrating the form of a Gill aging thermostat used for evaluation of Examples.

A moisture-hardening polyurethane hot-melt adhesive according to one embodiment of the present invention (this embodiment) includes a urethane prepolymer composed of a polyisocyanate component containing at least an aliphatic diisocyanate modified body and a polyvalent It is obtained from the reaction of alcohol components and has an isocyanate group at its end.

Here, the average number of functional groups of the isocyanate groups in the polyisocyanate component is 2.0 to 3.0, and the polyol component contains 1 to 8 mass % of a trifunctional or higher polyfunctional polyol.

The urethane prepolymer is a reaction product obtained by reacting the above-mentioned polyisocyanate component and the above-mentioned polyol component, and may contain other components during the reaction.

In this embodiment, it was found that it is possible to provide a non-yellowing and odorless moisture-curable polyurethane hot-melt adhesive that has excellent light resistance by using the following specific aliphatic diisocyanate modified body, It can reduce odor during work, and by introducing polyfunctional polyols with three or more functions, the texture of leather can be maintained, and it has various excellent properties (heat resistance, creep resistance, processability, stability over time, softness, Cold-resistant bending and bonding strength, etc.).

Hereinafter, the moisture-curable polyurethane hot-melt adhesive of this embodiment will be described in detail.

(polyisocyanate component)

As described above, in this embodiment, a modified aliphatic diisocyanate is included as the polyisocyanate component. By including an aliphatic diisocyanate modified body, good light resistance and odor reduction can be achieved.

The aliphatic diisocyanate modified body in this embodiment means: the isocyanurate body of aliphatic diisocyanate (ureaate polyisocyanate: for example, "TKA100" manufactured by Asahi Kasei Co., Ltd., Mitsui Chemical Co., Ltd. "D376N" manufactured by ), "IDT-70B" manufactured by Vencorex, etc.), allophanate body of aliphatic diisocyanate (allophanate diisocyanate: for example, "A201H" manufactured by Asahi Kasei Co., Ltd. ", "C-2770" manufactured by Tosoh Co., Ltd., etc.), biuret form of aliphatic diisocyanate (biuret type diisocyanate: for example, "24A-100" manufactured by Asahi Kasei Co., Ltd., etc.), Or the addition of aliphatic diisocyanate and polyol (Adduct type diisocyanate: for example, refers to diisocyanate adducts of diols such as "D201" manufactured by Asahi Kasei Co., Ltd. and "D-160N" manufactured by Mitsui Chemicals Co., Ltd.).

In this embodiment, from a practical viewpoint, it is preferable to use an allophanate diisocyanate alone or at least include an allophanate diisocyanate as an aliphatic diisocyanate modified body.

Examples of the aliphatic diisocyanate that is a raw material component of the aliphatic diisocyanate modified body include: 1,6-hexamethylene diisocyanate, isophorone diisocyanate, and 1,5-pentamethylene diisocyanate. .

Furthermore, unmodified polyisocyanate may be used together within the range that does not cause problems with the effects of the present invention.

Here, the isocyanurate system is a terpolymer of diisocyanate. Allophanate systems are obtained by adding urethane groups formed by the reaction of diisocyanates and alcohols to diisocyanates. Biuret systems are obtained by adding a ureylene group formed by the reaction of diisocyanate with water or amine and diisocyanate. The adduct is obtained by adding diisocyanate and polyol.

In this embodiment, the average number of functional groups of the isocyanate groups in the polyisocyanate component is 2.0~3.0, preferably 2.0~2.8, more preferably 2.0~2.4. If the average functional group number is less than 2.0, the film will not exhibit sufficient physical properties after hardening; if it exceeds 3.0, the stability over time will be poor, or when used for synthetic artificial leather, the texture, cold-resistant bending, or softness of the leather will be poor. .

Regarding the average number of functional groups of isocyanate groups in the above polyisocyanate components, when using a When using one modified aliphatic diisocyanate, it indicates the number of isocyanate functional groups. When using multiple types of modified aliphatic diisocyanates, it indicates the number of functional groups of each modified aliphatic diisocyanate and the number of polyisocyanate components. The total number obtained by multiplying the molar ratio (mol%).

For example, when 50 mol% of a bifunctional aliphatic diisocyanate modified body and 50 mol% of a trifunctional aliphatic diisocyanate modified body are combined, the average number of functional groups is 2×0.5+3×0.5=2.5. In addition, when the calculation result contains a value below the second decimal place, the second decimal place will be rounded off.

As a preferred aspect of the aliphatic diisocyanate modified body of the present embodiment, from the viewpoint of more reliably exerting the effects derived from the aliphatic diisocyanate modified body, a combination including any of the following is more preferred: .

(1) Combination of allophanate diisocyanate and adduct diisocyanate (especially diisocyanate adduct of diol)

(2) A combination of two or more allophanate diisocyanates with different structures

(3) Combination of allophanate diisocyanate and/or adduct diisocyanate (especially diisocyanate adduct of diol) and ureaate polyisocyanate

In the case of a combination of the above (1) and (2), that is, between an allophanate type diisocyanate (such as the above "A201H", "C-2770", etc.) and an adduct type diisocyanate (especially Diol diisocyanate adducts, such as the above-mentioned "D201", etc.) are combined, or when two or more allophanate-type diisocyanates with different structures are included (for example, the above-mentioned "A201H" and "C- 2770"), preferably 30:70~70:30 (polyisocyanate The blending ratio of ester components = molar ratio), preferably 60:40~40:60 (molar ratio).

Also, in the case of a combination of the above (3), that is, between an allophanate type diisocyanate and/or an adduct type diisocyanate (especially a diol diisocyanate adduct) and a urea ester type When polyisocyanates (such as the above-mentioned "TKA100", "D376N", etc.) are combined, the urea-type polyisocyanate is preferably 10 to 37 mol%, and more preferably 15 to 32 mol% of the total polyisocyanate components. . By setting the blending ratio of urea type polyisocyanate to 10 to 37 mol%, the desired leather texture or cold-resistant bending properties can be easily obtained.

Furthermore, as the urea-type polyisocyanate, 1,6-hexamethylene diisocyanate or 1,5-pentamethylene diisocyanate can be used, for example, considering that it has low viscosity and can obtain good handling properties and processing. Adaptability, increased cross-linking density to achieve high durability, preferably 1,5-pentamethylene diisocyanate ureaate polyisocyanate.

Furthermore, unmodified polyisocyanate may be used together within the range that does not cause problems with the effect of the present invention. In all polyisocyanate components, the ratio of modified aliphatic diisocyanate is preferably 95 mol% or more. More preferably, it is 98 mol%. By making it 95 mol% or more, the effect derived from the aliphatic diisocyanate modified body (especially the odor reduction effect) can be exerted more reliably.

(polyol component)

As mentioned above, the polyol component contains 1 to 8% by mass of a trifunctional or higher polyfunctional polyol. When the polyfunctional polyol is less than 1% by mass, sufficient heat creep resistance required as an adhesive for synthetic artificial leather cannot be obtained; when it exceeds 8% by mass, the stability over time, or the texture and softness of the leather will be deteriorated. reduce. The polyfunctional polyol is preferably 1 to 5% by mass, more preferably 2 to 4% by mass. %.

In this way, by blending a trifunctional or higher functional compound in a specific amount in any of the combinations (1) to (3) of the polyisocyanate component blended with the above-mentioned aliphatic diisocyanate modified body at an appropriate ratio. The polyol component exhibits a good effect of increasing the thermal softening point. As a result, an adhesive having both heat creep resistance and texture (cold resistance to bending) can be obtained.

Examples of polyfunctional polyols having three or more functions include: glycerin, trimethylolpropane, 1,2,5-hexanetriol, 1,2,6-hexanetriol, pentaerythritol, polyethylenetriol, polyethylenetriol, Propylene triol, polyoxypropylene triol, polyoxyethylene triol, polyoxyethylene propylene triol, etc.

Among them, from the viewpoint of good gel fraction or heat-resistant creep properties, trimethylolpropane and polyoxypropylene triol are preferred, and trimethylolpropane is even more preferred.

From the viewpoint of good heat creep resistance, gel fraction, etc., the number average molecular weight of the multifunctional polyol is preferably 100 to 1000, more preferably 100 to 200.

By setting the number average molecular weight to 100~1000, good synthesis stability is maintained and the desired effect can be easily obtained.

Polyols other than polyfunctional polyols with three or more functions are bifunctional polyols used in polyurethane. Examples include polycarbonate polyols, polyether polyols, polyester polyols, and polylactone polyols. Alcohols, polyolefin polyols, polymethacrylate diols, polysiloxane polyols, etc.

Furthermore, the number average molecular weight of the bifunctional polyol is preferably 500 to 6000, more preferably 700 to 4000, and examples thereof include the following.

(1)Polycarbonate polyol

Examples of the polycarbonate polyol include polybutylene carbonate diol, polypentylene carbonate diol, polyneopentyl carbonate diol, polyhexylene carbonate diol, poly(carbonate-1 , 4-cyclohexane dimethyl ester) diol, and these random/block copolymers, etc.

(2)Polyether polyol

Examples of the polyether polyol include those obtained by polymerizing or copolymerizing any of alkylene oxides (ethylene oxide, propylene oxide, butylene oxide, etc.) and heterocyclic ethers (tetrahydrofuran, etc.). Specific examples include: polyethylene glycol, polypropylene glycol, polyethylene glycol-polytetramethylene glycol (block or random), polytetramethylene ether glycol and polyhexamethylene ether glycol. wait.

(3)Polyester polyol

Examples of the polyester polyol include aliphatic dicarboxylic acids (for example, succinic acid, adipic acid, sebacic acid, glutaric acid, azelaic acid, etc.) and aromatic dicarboxylic acids (for example, meta- at least one of phthalic acid, terephthalic acid, etc.) and low molecular weight glycols (for example, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1, It is formed by the condensation polymerization of 4-butanediol, 1,6-hexanediol, neopentyl glycol and 1,4-bishydroxymethylcyclohexane, etc.).

Specific examples include: polyethylene adipate diol, polybutylene adipate diol, polyhexamethylene adipate diol, polyneopentyl adipate diol, polyhexane Ethylene glycol/butylene diol, polyneopentyl adipate/hexyl diol, poly3-methylpentane adipate diol and polybutylene isophthalate diol wait.

(4)Polylactone polyol

Examples of the polylactone polyol include polycaprolactone diol, poly-3-methylvalerolactone diol, and the like.

(5)Polyolefin polyol

Examples of the polyolefin polyol include polybutadiene glycol, polyisoprene glycol, or hydrogenated products thereof.

(6)Polymethacrylate diol

Examples of the polymethacrylate diol include α,ω-polymethyl methacrylate diol, α,ω-polybutyl methacrylate diol, and the like.

(7)Polysiloxane polyol

The polysiloxane polyol is preferably dimethylpolysiloxane. Since it can impart lubricity, it is particularly suitable for use as a coating agent.

These polyols can be used alone or in combination of two or more types.

Furthermore, in this specification, the "number average molecular weight" is the number average molecular weight (Mn) converted to polystyrene, which can usually be determined by gel permeation chromatography (GPC) measurement.

The moisture-curable polyurethane hot-melt adhesive of this embodiment contains an urethane prepolymer having an isocyanate group at its terminal. The urethane prepolymer is composed of a polyisocyanate component containing at least the above-mentioned aliphatic diisocyanate modified body. Specifically, the urethane prepolymer can be produced by reaction with the above-mentioned polyol component. Specifically, the urethane prepolymer can be produced as follows: the polyisocyanate component, the polyol component, and the optional chain extender, etc. are mixed with The equivalent ratio of isocyanate groups to hydroxyl groups (NCO/OH) becomes 1.5~ 2.0 is prepared, and the reaction is carried out at 40~150°C (preferably 60~110°C) through a one-step method or a multi-stage method until the reaction product reaches the theoretical NCO%.

As mentioned above, the equivalent ratio (NCO/OH) of the isocyanate group of the isocyanate component to the hydroxyl group of the polyol component is preferably 1.5 to 2.0, more preferably 1.3 to 2.2. By setting the equivalent ratio (NCO/OH) to 1.5~2.0, gel will not be produced and the viscosity suitable for processing can be achieved.

Examples of the chain extender include short-chain diols, short-chain diamines, and the like.

Compounds with short-chain diol series whose number average molecular weight is less than 500 include: ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, Aliphatic glycols such as 1,6-hexanediol and neopentyl glycol and their alkylene oxide low molar adducts (number average molecular weight less than 500); 1,4-bishydroxymethylcyclohexane and Alicyclic glycols such as 2-methyl-1,1-cyclohexanedimethanol and their alkylene oxide low molar adducts (number average molecular weight less than 500); aromatic glycols such as benzylene glycol and its alkylene oxide low molar adducts (number average molecular weight less than 500); bisphenols such as bisphenol A, thiodiphenol and sulfodiphenol and their alkylene oxide low molar adducts (quantity The average molecular weight is less than 500); and compounds such as C1~C18 alkyldiethanolamines and other alkyldialkanolamines. Furthermore, glycols containing ionic groups such as carboxyl groups, sulfo groups, phosphate groups, and amine groups can also be used.

Examples of short-chain diamines include: aliphatic diamine compounds such as ethylenediamine, trimethylenediamine, hexamethylenediamine, and octamethylenediamine; phenylenediamine, 3,3'-diamine, etc. Chloro-4,4'-diaminodiphenylmethane, 4,4'-methylenebis(aniline), 4,4'-diaminodiphenyl ether and 4,4'-diaminodiphenyl ether Aromatic diamine compounds such as cyclopentanediamine, cyclohexanediamine, 4,4-diamine dicyclohexylmethane, 1,4-cyclohexanediamine and isophoronediamine and other alicyclic diamine compounds ;Hydrazine, carbodihydrazine, adipic acid dihydrazide Hydrazine, dihydrazine sebacic acid, dihydrazine phthalate, etc.

Moreover, in the above-mentioned manufacturing method, a catalyst may be used as needed. Examples include: salts of metals and organic and inorganic acids such as dibutyltin dilaurate, dioctyltin dilaurate, stannous octoate, lead octoate, and tetra-n-butyl titanate; and organic metal derivatives; triethyl Organic amines such as amines; diazabicycloundecene catalysts, etc.

The urethane prepolymer of this embodiment is preferably reacted under solvent-free conditions without using organic solvents. In this way, a solvent-free urethane prepolymer can be produced.

From the viewpoint of processability and leather texture, the NCO% (isocyanate group content) of the resin component (urethane prepolymer) of the present embodiment is preferably 2 to 4%, and more preferably 2.5 to 3.7. %.

Furthermore, NCO% is a theoretical value obtained by calculation and can be obtained by the following formula.

NCO% (theoretical value) = [(The amount of isocyanate) × (NCO% of isocyanate) × (1-NCO/OH)/(NCO/OH)]/[The amount of isocyanate + the amount of polyol + additives The amount of preparation]

The moisture-curable polyurethane hot-melt adhesive of this embodiment preferably contains more than 90 mass% of the above-mentioned urethane prepolymer, and more preferably consists of the polyurethane prepolymer (ie, 100 mass%).

Here, when the moisture-curable polyurethane hot-melt adhesive of the present embodiment contains 90 mass % or more and less than 100 mass % of the above-mentioned urethane prepolymer, it is preferable to further contain an isocyanate-based cross-linking agent. By including an isocyanate-based cross-linking agent, compared to not containing an isocyanate-based cross-linking agent In the case of an adhesive, it can prevent the bonded materials from peeling off from each other caused by the adhesive.

When an isocyanate cross-linking agent is contained, the content of the isocyanate cross-linking agent in the moisture-curable polyurethane hot-melt adhesive of the present embodiment is preferably 10 mass % or less relative to the urethane prepolymer. More preferably, it is 1-7 mass %, and still more preferably, it is 1-5 mass %.

The isocyanate-based cross-linking agent is preferably a modified aliphatic diisocyanate, and specific examples thereof include the above-mentioned modified aliphatic diisocyanate.

Furthermore, the aliphatic diisocyanate modified form of the above-mentioned urethane prepolymer and the isocyanate cross-linking agent of this embodiment may be the same or different.

From the viewpoint of processability and leather texture, the NCO% (isocyanate group content) of the resin component of the present embodiment (when it contains a urethane prepolymer and a cross-linking agent) is preferably 2 to 4 %, preferably 2.5~3.7%.

In addition, NCO% when a urethane prepolymer and a cross-linking agent are included is a calculated theoretical value and can be obtained by the following formula.

NCO% (theoretical value) = [(NCO% of urethane prepolymer) × (amount of urethane prepolymer) + (NCO% of cross-linking agent) × (amount of cross-linking agent)]/[(amine The amount of ester prepolymer + the amount of cross-linking agent)]

The moisture-curable polyurethane hot-melt adhesive containing an isocyanate-based cross-linking agent can be produced by adding a predetermined amount of an isocyanate-based cross-linking agent after preparing the above-mentioned urethane prepolymer, stirring, etc., and mixing.

In addition, in the moisture-curable polyurethane hot-melt adhesive of this embodiment, an appropriate amount of thermoplastic polymer, adhesion-imparting resin, catalyst, pigment, antioxidant, light stabilizer, ultraviolet absorber, surfactant, Flame retardants, fillers, foaming agents, etc.

Here, various light stabilizers can be used, and preferred examples include hindered amine-based light stabilizers.

If a specific amount of a hindered amine light stabilizer is added to the urethane prepolymer of the present invention as described above, excellent effects such as increased gel fraction and shortened curing time can be obtained.

As the hindered amine light stabilizer, for example, bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis(1,2,2,6, sebacate) can be used. 6-pentamethylpiperidin-4-yl) ester, 1,2,3,4-butanetetracarboxylic acid tetrakis (2,2,6,6-tetramethyl-4-piperidinyl) ester, 1 ,2,3,4-butanetetracarboxylic acid tetrakis (1,2,2,6,6-pentamethyl-4-piperidinyl) ester, 1,2,3,4-butanetetracarboxylic acid ( Mixed 2,2,6,6-tetramethyl-4-piperidinyl/tridecyl) ester, 1,2,3,4-butanetetracarboxylic acid (mixed 1,2,2,6,6 -Pentamethyl-4-piperidinyl/tridecyl) ester, 8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-tri Azaspiro[4.5]decane-2,4-dione, etc. Among them, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate is preferred.

In addition, these compounds may be used individually or in combination of 2 or more types.

Furthermore, the moisture-hardening polyurethane hot-melt adhesive of this embodiment is used for synthetic artificial leather, that is, it is preferably an adhesive for synthetic artificial leather.

The moisture-curable polyurethane hot-melt adhesive of this embodiment can easily bond the adherends to each other by coating them on the surface of the adherends. Examples of the adherend include, in addition to the base material for synthetic artificial leather mentioned above, base materials of metals and non-metals (polycarbonate, glass, etc.).

Here, the gel fraction of the moisture-curable polyurethane hot-melt adhesive of this embodiment is preferably 85% or more, more preferably 90% or more.

If the gel fraction is 85% or more, heat creep resistance, alcohol resistance, and processability (hardening speed) can be improved. In order to increase the gel fraction, for example, the above-mentioned hindered amine light stabilizer can be added to the urethane prepolymer. From the viewpoint of obtaining the desired effects (higher gel fraction, shortened curing time, etc.), the addition amount is preferably 0.2 to 1.0% by mass, more preferably 0.2% relative to the urethane prepolymer. ~0.5 mass%. The gel fraction can be measured by the method described in the Examples.

The heat softening point (thermal hardening temperature) of the moisture-hardening polyurethane hot-melt adhesive of this embodiment after hardening is preferably 175°C or higher, and more preferably 185~220°C.

If the thermal softening point after hardening is 175°C or above, the thermal creep resistance, weather resistance, heat resistance, and industrial washing resistance will be improved. By improving weather resistance and heat resistance, it can be used as an adhesive for vehicle exterior components. By improving industrial washing resistance, it can be used for sanitary materials that require high-temperature sterilization.

The thermal softening point can be measured by the method described in the Examples. In addition, in this specification, the thermal softening point or the following elongation at break is measured after thermal hardening, which means after the disappearance of NCO is confirmed by IR (infrared radiation) measurement.

The elongation at break of the moisture-hardening polyurethane hot melt adhesive of this embodiment at 25°C after hardening is preferably 300 to 1000%, more preferably 400 to 800%. If the elongation at break is 300% With the above, when it is made into synthetic leather, the flexibility can be improved. If the elongation at break is 1,000% or less, the reduction in heat resistance creep properties and adhesive strength can be suppressed, making it easier to perform a good function as an adhesive.

The elongation at break can be measured by the method described in the Examples.

[Example]

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these. In addition, "parts" below means parts by mass, and "%" means mass %. In the table, (the number in parentheses) represents "the molar ratio (mol%) in the polyisocyanate component."

The materials used are described below.

(1)Polyester polyol

． TPEP85: Adipic acid/1,4-butanediol (60/40mol%) (number average molecular weight 2000, manufactured by Taijing Chemical)

(2)Polyether polyol

． PTMG1000: Number average molecular weight 1000, manufactured by Mitsubishi Chemical Co., Ltd.

． PPG1000: Number average molecular weight 1000, manufactured by Asahi Glass Co., Ltd.

(3) 3-functional polyol

． T-700: Polyoxypropylene triol, number average molecular weight 700, manufactured by Mitsui Chemicals Co., Ltd.

． TMP: Trimethylolpropane, number average molecular weight 134, manufactured by Mitsubishi Gas Chemical Co., Ltd.

(4)Polyisocyanate component

． A201H: Duranate A201H, a modified form of 1,6-hexamethylene diisocyanate and an allophanate type diisocyanate, weight average molecular weight 488.4, NCO%=17.2, manufactured by Asahi Kasei Co., Ltd.

． D201: Duranate D201, a modified form of 1,6-hexamethylene diisocyanate and a diisocyanate adduct of diol, weight average molecular weight 558.2, NCO%=15.9, manufactured by Asahi Kasei Co., Ltd.

． TKA100: Urea ester polyisocyanate of hexamethylene diisocyanate, weight average molecular weight 578, manufactured by Asahi Kasei Co., Ltd.

． C-2770: Allophanate diisocyanate of hexamethylene diisocyanate, weight average molecular weight 437.5, manufactured by Tosoh Co., Ltd.

． D376N: 1,5-pentane diisocyanate ureate type polyisocyanate, weight average molecular weight 536.1, manufactured by Mitsui Chemicals Co., Ltd.

． HDI: Hexamethylene diisocyanate, manufactured by Asahi Kasei Co., Ltd.

Furthermore, the above-mentioned "A201H" and "C-2770" both refer to the allophanate diisocyanate of hexamethylene diisocyanate, but they are different from each other in terms of weight average molecular weight, structure, etc.

(5)Light stabilizer

． HALS (hindered amine light stabilizer): CHISORB770 (LS770, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate)

[Example 1]

Mix 55 parts of polyester polyol (TPEP85) and 45 parts of polyether polyol (PTMG1000) as polyol components in a glass reaction vessel equipped with a mixer, a thermometer, a gas inlet, etc. parts and 3.0 parts of polyfunctional polyol (T-700) with three or more functions, and 30 parts of Duranate A201H and 30 parts of Duranate D201 as polyisocyanate components. The reaction vessel is heated and depressurized for dehydration, and then sealed. Nitrogen, stir for 120 minutes with the internal temperature at 110°C, and react to obtain an urethane prepolymer with NCO/OH=1.7. Next, a light stabilizer was added so as to become 0.3% with respect to the obtained urethane prepolymer (0.3% with respect to the resin), and the mixture was stirred for 30 minutes.

[Examples 2 to 10, Comparative Examples 1 to 10]

A urethane prepolymer was obtained in the same manner as in Example 1 except that the types or compositions of the polyol component, polyisocyanate component, etc. were as shown in Table 1 and Table 2 below. Furthermore, for Examples 3 to 8 and 10 and Comparative Examples 1 to 10, no light stabilizer was added after the urethane polymer was synthesized.

The following evaluation was performed using the urethane prepolymers obtained in Examples and Comparative Examples. The results are shown in Table 1 and Table 2.

[Gel fraction and resin properties]

(Preparation of film for evaluation)

The urethane prepolymer of each example was melted at 100° C. and applied to the release paper so that the film thickness after coating became 50 to 70 μm. Thereafter, as an aging step, the film was aged for 60 hours in an environment with a temperature of 40°C and a relative humidity of 60%, and then stored at room temperature (20°C) for 1 day to obtain an evaluation film with a release paper attached.

This evaluation film is used to evaluate gel fraction and resin physical properties.

<Gel fraction>

The film for evaluation obtained by peeling off the release paper was cut into 8 cm×8 cm pieces, and the weight (W-a) was measured. The weight-measured membrane was immersed in MEK (methyl ethyl ketone) and toluene respectively, covered with a lid to make a sealed product, left at 25°C for 2 hours, and then completely dried at 70°C. The weight of the completely dried film (W-b) was measured. Calculate the gel fraction using the formula (W-b)/(W-a)×100. If both MEK and toluene are above 85% in any case, it is qualified.

<20% modulus, 100% modulus, 300% modulus, breaking strength and breaking elongation>

The film for evaluation obtained by peeling off the release paper was punched into a dumbbell-shaped test piece in accordance with JIS3, and measured at room temperature (25°C) using an automatic stereographer AGS-J manufactured by Shimadzu Corporation using the measurement method in accordance with JISK-6251. 20% modulus, 100% modulus, 300% modulus (ML (MPa)), breaking strength (MPa) and elongation at break (%). In this evaluation, the higher the breaking strength, the higher the strength of the film. In addition, as an adhesive for synthetic artificial leather, the elongation at break is preferably 300 to 1000%.

In addition, regarding the 300% modulus of Comparative Examples 3 and 5, since the film was not stretched to 300% (harder), there was no measured value, so it was recorded as "-" in Table 2.

<Thermal softening point>

The thermal softening point was measured using the evaluation film (width 1.5 cm, length 6 cm) obtained by peeling off the release paper.

Specifically, first, as shown in FIG. 1 , clamps 12 are installed above and below the evaluation film 10 , and then the clamps 12 are fixed with Sellotape (registered trademark), and a force of 450 g/cm ² is applied to one of the clamps 12 while hanging. In the manner of loading, a plumb 14 is installed on the jig 12 and a sample 16 is produced. In addition, 2 cm in the longitudinal direction of the central portion of the evaluation film 10 was not covered by Sellotape (registered trademark).

Next, as shown in FIG. 2 , the fixture 12 of the sample 16 without the plumb 14 is installed on the turntable 22 of the Gill aging thermostat 20 . Thereafter, the turntable 22 was rotated at 5 rpm, and the temperature inside the Gill aging thermostat 20 was raised from room temperature at a speed of 3°C/min. The temperature (° C.) at which the evaluation film 10 breaks or is stretched to 2 times is defined as the thermal softening point.

In this evaluation, the higher the thermal softening point (thermal softening temperature), the higher the durability (heat resistance) of the film.

[Evaluation of adhesive]

<Heat creep resistance>

As a creep test, a test is performed in which a certain load is applied to a test piece under high temperature for a long time and the amount of deformation or the time until fracture is measured. Specifically, proceed as follows 1) to 8) below.

1) Place the moisture-hardening PUR-HM (polyurethane reactive-hot melt, polyurethane reactive hot melt) resin (urethane prepolymer in each example) and the coating rod of the test object into an oven at 110°C for preheating. hot.

2) Coat the PU (polyurethane, polyurethane) resin surface of the wet film-forming cloth (A) with PUR-HM resin at 200μ intervals (thickness 200μm), and immediately adhere to the PU resin surface of the wet film-forming cloth (B) .

Furthermore, as the wet film-forming cloth (A) and the wet film-forming cloth (B), the following synthetic artificial leather was used. This synthetic artificial leather was coated with a polyurethane resin preparation liquid using DMF as a medium on a nonwoven fabric used as a base material. (A preparation made by diluting RESAMINE CU-4340NS (PU resin solid content 30%, manufactured by Dainichi Seika Co., Ltd.) to 15% solid content using DMF), solidifying in a water tank, removing DMF, and drying Obtained, and the synthetic artificial leather is formed with a porous layer with a thickness of 800 to 1000 μm after drying on the base material.

3) After the above-mentioned bonded product is cured at 25°C/60%RH for 24 hours, the heat resistance is measured according to the following procedure.

4) Set the oven to 170°C. Also, cut a piece of the bonded product with a width of 3cm and a length of 12cm or more to prepare a test piece.

5) Peel off the end of the test piece at the joint surface, install fixing fixtures on the wet film-forming cloth (A) side and the wet film-forming cloth (B) side, and hang a 3kg plumb on one side.

6) After placing the test sample in an oven at 170°C, close the oven door immediately.

7) After closing the door, leave it for 5 minutes.

8) After 5 minutes, take out the test piece immediately, place it at 170°C for 5 minutes, observe the peeling length and peeling state, and evaluate according to the following evaluation criteria. In addition, ○ means passed.

[Evaluation criteria]

○: The length of peeling is less than 2cm, and the peeling state is that the base material is broken.

△: The length of peeling is more than 2cm and less than 5cm, and the peeling state is that the base material is broken.

×: The length of peeling is more than 5cm, or the wet PU resin layer is peeled off on all sides

<Processing properties (initial curability)>

The urethane prepolymer obtained in the Examples and Comparative Examples was melted at 100° C. and coated on release paper so that the film thickness became 50 to 70 μm. Under the condition of 40℃, perform the operation of bonding the non-coated surface of the same substrate every 30 seconds for 5 minutes. The processing (initial curing) performance is evaluated based on the resistance felt when peeling off the bonded base material by hand and the amount of resin adhered to the base material.

○: There is no resistance during peeling and no adhesion, so it is passed.

△: There is resistance during peeling, but no adhesion. The evaluation is worse than ○.

×: There was resistance during peeling and there was also adhesion, so it failed.

(Production and evaluation of synthetic artificial leather)

(Formation of epidermal layer)

RESAMINE NE-8875-30 (manufactured by Dainichi Seika Co., Ltd.) as a solvent-based urethane resin, SEIKASEVEN BS-780 (manufactured by Dainichi Seika Co., Ltd.) as a colorant for synthetic artificial leather, and diluent The solvents methyl ethyl ketone (MEK) and dimethylformamide (DMF) are mixed, and then evenly coated on the release paper with a coating amount of 250 μm/wet by a rod coater, and then dried at 120°C. Dry for 5 minutes to obtain an epidermal layer with a film thickness of 40~50 μm, which is used as the epidermis of synthetic artificial leather.

(Production of standard synthetic artificial leather for leather texture evaluation)

The skin layer formed on the above-mentioned release paper is coated with 100 parts by mass of RESAMINE UD-8351NT (polyurethane resin adhesive, manufactured by Dainichi Seika Industry Co., Ltd.) and C-50 cross-linking agent (isocyanate cross-linking agent, Dainichi Seika Co., Ltd.). An adhesive layer prepared with a composition of 10 parts by mass (manufactured by Nissei Chemical Industry Co., Ltd.) was formed into an adhesive layer with a thickness of 100 μm. The adhesive layer was obtained after predrying at 80°C for 2 minutes. The lamination roller temperature was 40°C. , perform pressure bonding on the adhesive layer and the base material (fabric). Thereafter, aging was performed under the conditions of 50°C/48 hours to obtain standard synthetic artificial leather for softness evaluation.

(Preparation of synthetic artificial leather of Examples 1 to 10 and Comparative Examples 1 to 10)

The polyurethane prepolymer obtained in the Examples and Comparative Examples was heated at 100°C, and coated on the skin layer formed on the release paper so that the coating film thickness became 100 μm. The lamination roller temperature was 30°C. Next, press it with the base fabric (fabric). As the aging step, it is aged for 5 days in an environment with a temperature of 40°C and a relative humidity of 60%. Peels off from release paper, made using polyurethane prepolymer Synthetic artificial leather was used for evaluation.

<Leather texture>

The softness of each obtained synthetic artificial leather for evaluation was compared based on the tactile feel of the standard synthetic artificial leather as a standard. The evaluation indexes are as follows. In addition, if the evaluation is ○, the result is passed.

○: As soft as standard synthetic leather (passed in terms of leather texture)

×: Very hard compared to standard synthetic leather (unsatisfactory in terms of leather texture)

<Cold resistance bending test>

Each synthetic artificial leather obtained above was made into a test piece with a width of 50 mm and a length of 150 mm (evaluation range: 100 mm). Using this test piece, a De Mattie type testing machine (manufactured by Yasuda Seiki Seisakusho, model: NO.119-L DEMATTIA FLEXING TESTER), conduct bending tests in a -10°C environment, a stretching and bending range of 72~108%, and a low temperature of -10°C. The evaluation indicators are as follows. In addition, if the evaluation is ○, the result is passed.

○：-10℃, more than 30,000 times

×: -10℃, less than 30,000 times

<Time stability: Pot Life>

The urethane prepolymers obtained in the Examples and Comparative Examples were melted at 100°C, and the change in viscosity over time was evaluated at 100°C for 24 hours, and the precipitate was visually evaluated (usable level is ○) .

○: No sediment, viscosity change does not reach +100%.

×: Precipitates are present and the viscosity change is +100% or more.

In addition, the viscosity is measured under the following conditions.

(viscosity measurement)

The viscosity of each urethane prepolymer was measured using a BM type viscometer (Tokyo Keiki Manufacturing Co., Ltd.) under the conditions of rotor No. 4/30 rpm/100°C.

<stench>

The urethane prepolymers obtained in the Examples and Comparative Examples were put into a 250 ml pound jar and heated at 100° C. for 2 hours. Then, 10 sensory inspectors opened the lids to confirm the odor. The evaluation criteria are as follows (○ indicates practical level).

○: All 10 people did not feel any odor.

×: More than 5 out of 10 people felt smelly.

<Film-forming property>

The urethane prepolymer obtained in the Examples and Comparative Examples was heated to 100° C. and applied to release paper K8P (01) so that the coating film thickness became 100 μm. Immediately after coating, incubate at 40°C for 10 minutes. Film-forming properties were evaluated based on the continuity of the coating film after 10 minutes (○ indicates a practical level).

○：Maintain the continuity of the coating film

×: Crawling or shrinkage of the coating film occurs

<Curing time>

The urethane prepolymer obtained in the Examples and Comparative Examples was melted at 100°C, coated on release paper so that the film thickness was 50 to 70 μm, and then stored at 40°C/60RH%. IR measurement was performed every 12 hours, and the time when NCO disappeared was set as the curing time. Furthermore, the curing time was measured only for Examples 1, 3, and 8 to 10.

<Adhesion strength>

Use an iron at 140°C for 1 minute to apply the hot-melt tape to the upper surface of the resin layer of the synthetic artificial leather for the evaluation of each example used in the evaluation of the above <leather texture>, and cool it at room temperature for 1 hour. Afterwards, peel off the base fabric and the skin closely connected to the hot-melt tape, measure its strength using an automatic stereogrammeter, and set it as the bonding strength. Furthermore, as an adhesive for synthetic artificial leather, the measured value is preferably 1.2 kgf/cm or more.

In addition, "NCO% in the resin component" in Tables 1 and 2 is the NCO% in the obtained urethane prepolymer.

[Example 11]

Mix 55 parts of polyester polyol (TPEP85) and 45 parts of polyether polyol (PTMG1000) as polyol components in a glass reaction vessel equipped with a mixer, a thermometer, a gas inlet, etc. parts, and 3.0 parts of trifunctional or higher polyfunctional polyol (T-700), and 30 parts of Duranate A201H and 30 parts of Duranate D201 as polyisocyanate components, the reaction vessel is heated, depressurized and dehydrated, and then Nitrogen gas was sealed, and the reaction was carried out with stirring for 120 minutes while the internal temperature was 110°C, and an urethane prepolymer with NCO/OH=1.7 was obtained. Next, a light stabilizer was added in an amount of 0.3% with respect to the obtained urethane prepolymer (0.3% with respect to the resin), and further, TKA-100 (HDI (hexamethylene diisocyanate)) as an isocyanate cross-linking agent was added. Methyl diisocyanate) urea ester body) was adjusted to 2.0% (2.0% with respect to the resin), and stirred for 30 minutes to prepare a moisture-hardening polyurethane hot-melt adhesive.

The moisture-curable polyurethane hot-melt adhesive was evaluated as described above, and the following interlaminar peeling test was further performed. The results are shown in Table 3.

<Interlaminar Peeling Test>

1) Put the moisture-curing PUR-HM resin of the test object (the moisture-curing polyurethane hot-melt adhesive of Example 11 and the following Examples 12 to 15) and the coating rod into an oven at 110°C for preheating. hot.

2) Coat PUR-HM resin at 200μ intervals (thickness 200μm) on the epidermal layer obtained in (Formation of epidermis layer) in the above (Preparation and Evaluation of Synthetic Artificial Leather), and immediately combine it with the above-mentioned wet film-forming cloth (B) After the PU resin surface is bonded, the bonded product is hardened at 40℃/60%RH for 48 hours.

3) Use an iron at 140°C for 1 minute to press the hot-melt tape on the upper surface of the skin layer of the above-mentioned bonded product, that is, the resin layer. After cooling at room temperature for 1 hour, remove the base fabric and the hot-melt tape. The skin of the adhesive tape is peeled off, and the strength is measured using an automatic stereographic measuring instrument.

In addition, the strength was measured in the same manner as in Example 1 based on the peel strength.

The following evaluation indexes were used to evaluate the interlayer peeling strength in each Example. The results are shown in Table 3.

A: Compared with Example 1, the interlayer peeling strength is increased by more than 10%.

B: The interlayer peeling strength is the same as that of Example 1, or even if it is improved, it does not reach 10%.

C: Compared with Example 1, the interlayer peeling strength decreased.

[Examples 12~15]

A moisture-curable polyurethane hot-melt adhesive was produced in the same manner as in Example 11, except that the type of isocyanate-based cross-linking agent was changed to the cross-linking agent shown below.

Furthermore, "24A-100" manufactured by Asahi Kasei Co., Ltd. was used as the isocyanate-based cross-linking agent in Example 12, "D376N" manufactured by Mitsui Chemicals Co., Ltd. was used as the isocyanate-based cross-linking agent in Example 13, and Vencorex was used "IDT-70B" manufactured by the company was used as the isocyanate-based cross-linking agent in Example 14, and "D-160N" manufactured by Mitsui Chemicals Co., Ltd. was used as the isocyanate-based cross-linking agent in Example 15.

Using this moisture-curable polyurethane hot-melt adhesive, the same evaluation and tests as in Example 11 were performed. The results are shown in Table 3.

Furthermore, "NCO% in resin components" in Table 3 includes the obtained urethane prepolymer and NCO% in the case of cross-linking agent.

[Industrial availability]

The moisture-hardening polyurethane hot-melt adhesive of the present embodiment can be used for synthetic artificial leather, that is, it can be used as a base material for synthetic artificial leather. In addition to the base material for synthetic artificial leather, it can also be used for metals, non-metals (polycarbonate), etc. , glass, etc.) base material. In addition, since it has excellent heat resistance, it is also expected to be widely used in vehicle exterior components and hygienic materials that require high-temperature sterilization.

Claims (10)

A moisture-hardening polyurethane hot-melt adhesive that contains an urethane prepolymer obtained by the reaction of a polyisocyanate component containing at least an aliphatic diisocyanate modified body and a polyol component, And it has an isocyanate group at its end. The average number of functional groups of the isocyanate group in the above-mentioned polyisocyanate component is 2.0 to 3.0. The above-mentioned polyol component contains 1 to 8 mass % of a polyfunctional polyol with three or more functions. For example, the moisture-hardening polyurethane hot-melt adhesive of claim 1 has a gel fraction of more than 85%. The moisture-hardening polyurethane hot-melt adhesive of claim 1 or 2, wherein the aliphatic diisocyanate modified body includes an allophanate-type diisocyanate. The moisture-hardening polyurethane hot-melt adhesive of claim 1 or 2, wherein the aliphatic diisocyanate modified body includes a diisocyanate adduct of a diol. The moisture-hardening polyurethane hot-melt adhesive of claim 1 or 2, wherein the aliphatic diisocyanate modified body includes urea-type polyisocyanate. Such as the moisture-hardening polyurethane hot-melt adhesive of claim 5, wherein the polyisocyanate component contains 10 to 37 mol% of the above-mentioned urea ester type polyisocyanate. For example, the moisture-hardening polyurethane hot-melt adhesive of claim 1 or 2 has a thermal softening point of 175°C or above after hardening. For example, the moisture-hardening polyurethane hot-melt adhesive in claim 1 or 2 has an elongation at break of 300~1,000% at 25°C after hardening. Such as the moisture-hardening polyurethane hot-melt adhesive of claim 1 or 2, which further contains an isocyanate cross-linking agent. The moisture-hardening polyurethane hot-melt adhesive of claim 9, wherein the isocyanate cross-linking agent is an aliphatic diisocyanate modified body.