JP7728024B2 - Two-component urethane resin composition for synthetic leather and synthetic leather - Google Patents

Description

This invention relates to a two-component urethane resin composition for synthetic leather and synthetic leather made using the same.

Generally, synthetic leathers used in automobile seats, sports shoes, etc. are manufactured by overlaying and integrating a resin layer onto a knitted or woven fabric base.
Artificial leather, which has a similar structure to synthetic leather, uses a nonwoven fabric impregnated with a resin liquid as a base fabric, but the structure in which a resin layer is layered and integrated onto the surface of the base fabric is the same as that of synthetic leather, so in this invention, artificial leather is also referred to as synthetic leather.

Two-component urethane resins used in the resin layer of such synthetic leathers are known to be environmentally friendly, using bio-polyols and bio-chain extenders. One known example is a urethane resin-based prepolymer for synthetic leather that can be instantaneously heated and mixed in a mixer without using organic solvents, and then immediately applied to the base fabric (Patent Document 1).

Catalysts are also used to promote the reaction between the polyol, which is the main component of two-component urethane resins, and the isocyanate, which is the curing agent. Known catalysts include tertiary amine compounds, amines with isocyanate-reactive groups, and autocatalytic polyols based on amine initiators containing tertiary amine groups (Patent Document 2, paragraph 0068).

The above-mentioned autocatalytic amine polyol is a polyol compound in which catalytic functionality has been added to the main component polyol. For example, it is a polyol compound that imparts autocatalytic functionality, has a functionality of 2 to 8, a hydroxyl value of 15 to 200, and has at least one tertiary amine group, and is known to be used in the production of flexible polyurethane foams (Patent Document 3).

Patent No. 7295539 Special Publication No. 2003-533565 Special Publication No. 2007-535606

However, with the two-component urethane resin for synthetic leather described in Patent Document 1, the polyol (OH) component and isocyanate (NCO) component are heated individually or in a mixed state to lower the viscosity and allow the reaction to occur when preparing the prepolymer, which requires a lot of heat energy. Furthermore, after the urethane resin is applied, a lot of heat energy and time is required for drying and curing, and there are restrictions on the amount of filler that can be added, making it difficult to reduce costs.

To produce synthetic leather using the urethane resin-based prepolymer described above, a catalyst must be used just before the polyurethane resin is applied to the base fabric, and the prepolymer and polyol must be mixed instantaneously in an instantaneous mixer to quickly react the OH and NCO components. However, depending on the type and amount of catalyst used, the synthetic leather may be prone to bleed (discoloration) and its physical properties may be impaired.

Furthermore, the autocatalytic amine polyols disclosed in Patent Documents 2 and 3 contain an unspecified amount of 2 to 100% by weight of a polyol having a hydroxyl value of 15 to 200, blended into 100% by weight of a foamable polyol composition, and therefore cannot be said to be suitable for use in synthetic leather in terms of foaming, peel strength, and sense of unity.
In other words, it has not been previously anticipated that such an autocatalytic amine polyol would be used to formulate a two-component urethane resin for synthetic leather. Even if such an autocatalytic amine polyol were to be used accidentally, it would be difficult to adjust the heating temperature without impairing the quality in order to adjust the pot life for application to a base fabric or release paper, and it would be difficult to consistently obtain synthetic leather of environmentally friendly quality that has the required flexibility and peel strength resistance.

The objective of this invention is to solve the above-mentioned problems by providing a two-component urethane resin composition that can reduce the component ratio of prepolymers, which require a lot of thermal energy to manufacture, to 50% or less in the resin composition; and to provide a two-component urethane resin composition for synthetic leather that allows the curing reaction to proceed quickly by simply mixing the liquid base agent and curing agent at room temperature without the need for a large amount of catalyst, resulting in a urethane resin coating on synthetic leather that has excellent peel strength resistance and flexibility, or to provide synthetic leather using this two-component urethane resin composition.

To solve the above problems, this invention provides a two-component urethane resin composition for synthetic leather, which is composed of a base agent consisting of a mixture of a polyol compound and a chain extender, and a curing agent containing an isocyanate compound, and the polyol compound is a liquid polyol compound containing 1 to 15 mass% of an autocatalytic amine-based polyol containing two or more tertiary amine groups and three or more hydroxyl groups per 100 mass% of the polyol compound, and synthetic leather made using the same.

The above-mentioned autocatalytic amine polyol is preferably an amine polyether polyol having a hydroxyl value of 300 to 1,000 KOH mg/g, which is obtained by addition polymerization of propylene oxide (PO) or propylene oxide (PO) and ethylene oxide (EO) together with one or more amines selected from ethylenediamine, diethylenetriamine, toluenediamine, and tetraethylenepentamine.

In the two-component urethane resin composition for synthetic leather of this invention constructed as described above, the liquid polyol compound contained in the base contains a predetermined amount of a predetermined autocatalytic amine-based polyol. Therefore, simply by mixing the composition with the curing agent at room temperature, the liquid polyol and chain extender react quickly.
Therefore, there is less need to react polyol and isocyanate in advance to form a prepolymer, and the component ratio of the prepolymer in the resin composition can be reduced to 50% or less, resulting in a two-component urethane resin composition that contributes to energy savings and process reductions.

In addition, the reaction rate of the amine-based polyol containing two or more tertiary amine groups and three or more hydroxyl groups is appropriate, resulting in an appropriate pot life for synthetic leather production. Because no organic solvents are required for viscosity adjustment, the drying and curing time of the two-component urethane resin composition is shortened, and the thermal energy consumed in the manufacturing process is also significantly reduced.

The two-component urethane resin composition of this invention has a low-viscosity liquid base and curing agent, allowing for the use of relatively inexpensive fillers in the production of synthetic leather. Furthermore, the minimum amount of catalyst required is small, which helps prevent bleeding and deterioration of the physical properties of the synthetic leather.

When the base agent contains a biopolyol, a biochain extender, or both, the resulting two-component urethane resin composition is more resource-efficient and environmentally friendly. Furthermore, it is preferable to add a filler such as a biofiller to the base agent in order to create a two-component urethane resin composition that is more environmentally friendly, as described above.

Furthermore, by setting the R value, which is the equivalent ratio (isocyanate group/hydroxyl group) of the two-component urethane resin composition, to 1.0 to 1.4, the physical properties, such as the required usable time for application to a base fabric or release paper as synthetic leather, are stabilized.
Furthermore, synthetic leather whose base fabric surface is coated with the above-mentioned two-component urethane resin composition will more stably have the required quality characteristics such as flexibility and peel strength.

This invention has the advantage that the liquid polyol compound contains a predetermined amount of a specific autocatalytic amine polyol, eliminating the need to prepare large amounts of prepolymer in advance, which requires a lot of thermal energy during production. For example, even when the prepolymer component ratio is 50% by mass or less, the reactivity is excellent. The liquid base and curing agent can be mixed and rapidly cured at room temperature without heating, using a small amount of catalyst as needed. When applied to the surface of synthetic leather, the resulting two-component urethane resin composition for synthetic leather provides a urethane resin coating with excellent peel strength and flexibility. Furthermore, this composition can be used to obtain synthetic leather with excellent peel strength and flexibility.

The raw materials, blending ratios, and manufacturing conditions for the two-component urethane resin composition for synthetic leather, which is an embodiment of this invention, and the synthetic leather using it, are described in detail below. Where necessary, the abbreviations for chemical components are listed in parentheses after the general names.

<Autocatalytic amine polyol>
The autocatalytic amine polyol used in this invention has two or more tertiary amine groups (sometimes also referred to as N groups) and three or more hydroxyl groups, preferably has a hydroxyl value of 300 to 1000 KOHmg/g, and is preferably an amine polyether polyol.

Specific examples of amine-based polyols include those obtained by addition polymerization of propylene oxide (PO) and/or ethylene oxide (EO) with one or more amines selected from ethylenediamine, diethyltriamine, toluenediamine, and tetraethylenepentamine. Examples include commercially available products manufactured by addition polymerization of PO or PO together with EO, such as Sannix manufactured by Sanyo Chemical Industries, Ltd., including NP-300, NL-300, NL-270, NE-240, and AP-470.

These amine-based polyols are multifunctional polyols containing tertiary amine groups, have excellent reactivity with isocyanates, cure in an extremely short time, and serve as the main component for producing high-strength urethane resins.
In order to obtain such properties, it is more preferable that the amine-based polyol has two or more tertiary amine groups and 3 to 7 hydroxyl groups.

The amount of autocatalytic amine polyol added is preferably 1 to 15% by mass of the OH component, and more preferably 1 to 5% by mass. This is because if it is less than 1% by mass, the desired effect will not be sufficient, and if it exceeds 15% by mass, the resin will become hard, will not have sufficient flexibility, and will have a shorter usable life.

Furthermore, if the hydroxyl value is less than 300 KOHmg/g, the reactivity will be insufficient, making it difficult to quickly peel from the release liner, and if it exceeds 1000 KOHmg/g, the resin will become hard and its flexibility will be poor.

<Liquid polyol>
The liquid polyol used in the present invention is preferably one or more polyols selected from polyester polyols, polyether polyols, polycarbonate polyols, lactone polyols, and castor oil polyols, which are liquid at room temperature.
Incidentally, the normal temperature in this invention refers to the normal temperature defined by the Japanese Industrial Standards (JIS Z 8703), which is in the range of 20°C ± 15°C (5 to 35°C).

<Chain lengthener (also called chain extender)>
The chain extender used in this invention is preferably one or more selected from ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol (1,3PDO), 3-methyl-1,5-pentanediol (MPD), 2-methyl-1,3-propanediol (MPO), etc., which are liquid at room temperature. However, such chain extenders are used selectively depending on the use and purpose of the synthetic leather.

<Isocyanate>
Specific examples of the isocyanate used in the present invention include 4,4'-diphenylmethane diisocyanate (MDI), carbodiimide-modified MDI (liquid MDI), 2,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, and hydrogenated MDI. Dimers and trimers of these may also be used, and two or more of these may also be used in combination.

<Additive-1>
Specific examples of additives that may be used as needed in the present invention include antioxidants, ultraviolet absorbers, weather resistance agents, viscosity reducers, thickeners, thixotropy-imparting agents, flame retardants, silicone foam stabilizers, foaming agents, antistatic agents, hydrolysis inhibitors, plasticizers, retarders, moisture absorbers, and coupling agents.

<Additive-2>
Other additives include calcium carbonate, aluminum hydroxide, and talc, which have an average particle size of 100 μm or less and are highly dispersible; biofillers such as eggshell powder, seashell powder, apple powder, and wood flour (cellulose); glass balloons (hollow foams); microsphere powder foams; and diatomaceous earth, and two or more of these can be used in combination. As such additives (fillers), biofillers are preferred, particularly as they are environmentally friendly. For example, biofillers derived from eggshell powder and primarily composed of calcium carbonate (CaCO ₃ ), or recycled biofillers, can be used. An example of commercially available eggshell powder is eggshell powder (membrane-removed, average particle size 15 μm) manufactured by Green Techno 21 Co., Ltd.

The amount of additive-2, such as calcium carbonate, added can be 10 to 200 parts by mass per 100 parts by mass of the OH component, with 30 to 80 parts by mass being preferred. While this amount can be adjusted within the range of the instantaneous mixer's tolerance, adding too much is not recommended, as it will harden the synthetic leather and impair its flexibility and pliability.

<Catalyst>
The catalyst used in this invention is preferably an amine-based catalyst, including an acid-blocked type and a temperature-sensitive thermal dissociation type, and it is preferable to select and use one or more of these. Commercially available products of such catalysts include U-CAT (registered trademark, manufactured by San-Apro Co., Ltd.) SA102, which is a DBU-octylate salt and has a long working life, and U-CAT (registered trademark, manufactured by San-Apro Co., Ltd.) 1102, which is a DBN-octylate salt.

<Composition and manufacturing conditions>
(a) Polyol component Liquid polycarbonate has good hydrolysis resistance, and liquid polyether polyol has good low-temperature flexibility, and these can be selected and combined depending on the application. In addition, since the production process involves only mixing, including the liquid chain extender, a combination with good compatibility is preferred.

(b) Isocyanate Component The isocyanate compound is preferably liquid 4,4'-diphenylmethane diisocyanate (MDI) or a prepolymer with an NCO content of 7 to 30%. Prepolymers with an NCO group content of 7 to 30% have high viscosity and poor reactivity when the NCO content is less than 7%. When the NCO content is 30% or more, the prepolymer becomes hard and its flexibility deteriorates. The prepolymer component ratio in the resin component is preferably 0 to 50%. Using liquid MDI instead of the prepolymer reduces the viscosity and improves curability, but the prepolymer becomes slightly hard and its flexibility deteriorates slightly.

(c) R value [(isocyanate group/hydroxyl group) equivalent ratio]
The R value is preferably in the range of 1.0 to 1.4, because if it is less than 1.0, the reactivity will be slow and the physical properties will be insufficient, and if it exceeds 1.4, the resin will be hard and its flexibility will be poor.

(d) Liquid Temperature: The liquid is used at room temperature (for example, 25°C), but can be heated up to 50°C if necessary. However, as the temperature increases, the viscosity decreases, but the usable time also decreases, and the amount of catalyst must be reduced.

(e) Curing Time The curing time used in this invention is the total time including pre-drying and post-drying. Pre-drying is carried out under conditions that result in a semi-cured state with adequate tackiness and that does not penetrate the base fabric. Typically, a curing time of 2 minutes at 120°C is used as a guideline, and the amount of catalyst is adjusted so that the curing time is 2 to 3 minutes at 120 to 130°C.
The post-drying is carried out so that the pattern does not collapse and sufficient physical properties can be obtained even when the release paper is peeled off after the base fabric is bonded.

The polyol (OH) components (Production Examples 1-4) and isocyanate (NCO) components (Production Examples 5-6) used as the base resins were produced in the blending ratios shown in Tables 1 to 3 below, and comparative prepolymers (OH-R1, OH-R2) were also produced.
The raw materials used in the above production are listed below, with the abbreviations shown in Tables 1-3 written in brackets [ ]. Note that OHV shown below is the hydroxyl value, expressed in KOHmg/g, and f indicates the number of functional groups.

(1) Bio-liquid polyether polyol (SK Chemicals Corporation; ECOTRION H-2000, bifunctional (2f), hydroxyl value (OHV) = 56) [H-2000]
(2) Liquid polyether polyol (Sanyo Chemical Industries, Ltd.; Sannix PP-1000, 2f, OHV = 112) [PPG-1000]
(3) Bioliquid chain extender (manufactured by DuPont; 1,3PDO, 2f, OHV = 112) [1,3PDO]
(4) 4,4'-diphenylmethane diisocyanate [MDI]
(5) Autocatalytic amine polyol (ethylenediamine PO adduct polyol, manufactured by Sanyo Chemical Industries, Ltd.; Sannix NP-300, 4f, OHV=750) [NP-300]
(6) Autocatalytic amine polyol (diethylenetriamine PO adduct polyol, manufactured by Sanyo Chemical Industries, Ltd.; Sannix NP-400, 5f, OHV=700) [NP-400]
(7) Liquid polycarbonate dipolyol (Kuraray Co., Ltd.; C-2090, 2f, OHV=56) [C-2090]
(8) Liquid polyester dipolyol (Kuraray Co., Ltd.; P-2010, 2f, OHV=56) [P-2010]
(9) Liquid castor oil-based polyol (manufactured by Toyokuni Oil Mills; HS CM-025P, 3f, OHV = 200) [HS CM-025P]
(10) Carbodiimide-modified liquid MDI (Mitsui Chemicals, Inc.; Cosmonate LL) [liquid MDI]

(Production Example 1; OH-1a)
The above (1) bio-based liquid polyether polyol [H-2000], (2) liquid polyether polyol [PPG-1000], (3) bio-based liquid chain extender [1,3-PDO], and (5) amine-based polyol [NP-300] were mixed uniformly at room temperature for 15 minutes in the blending ratio shown in Table 1 to produce an OH component mixture "OH-1a" with an OHV of 115.72.

(Production Example 2; OH-1b)
In the blending ratio shown in Table 1, (1) bio-based liquid polyether polyol [H-2000], (2) liquid polyether polyol [PPG-1000], (3) bio-based liquid chain extender [1,3-PDO], and (6) amine-based polyol [NP-400] were uniformly stirred at room temperature for 15 minutes to produce an OH component mixture "OH-1b" with an OHV of 119.88.

(Production Example 3; OH-2a)
In the blending ratio shown in Table 1, (7) liquid polycarbonate dipolyol [C-2090], (8) liquid polyester dipolyol [P-2010], (9) liquid castor oil-based polyol [HS CM-025P], (3) bio-based liquid chain extender [1,3-PDO], and (5) amine-based polyol [NP-300] were uniformly stirred at room temperature for 15 minutes to produce an OH component mixture "OH-2a" with an OHV of 139.72.

(Production Example 4; OH-2b)
In the blending ratio shown in Table 1, (7) liquid polycarbonate dipolyol [C-2090], (8) liquid polyester dipolyol [P-2010], (9) liquid castor oil-based polyol [HS CM-025P], (3) bio-based liquid chain extender [1,3-PDO], and (6) amine-based polyol [NP-400] were uniformly stirred at room temperature for 15 minutes to produce an OH component mixture "OH-2b" with an OHV of 131.00.

(Production Example 5; NCO-1)
In the blending ratio shown in Table 1, (8) liquid polyester dipolyol [P-2010] kept at 60°C was added to (4) 4,4'-diphenylmethane diisocyanate [MDI] kept at 60°C, and the mixture was stirred at 80°C for 2 hours. After that, (10) carbodiimide-modified liquid MDI [liquid MDI] was added and the mixture was stirred at 80°C for 1 hour to produce an isocyanate component "NCO-1" with an NCO% of 22.35%.

(Production Example 6; NCO-2)
In the blending ratio shown in Table 1, (1) bio-based liquid polyether polyol [H-2000] and (2) liquid polyether polyol [PPG-1000] were mixed uniformly and stirred at 60°C, and (4) 4,4'-diphenylmethane diisocyanate [MDI] kept at 60°C was added, followed by stirring at 80°C for 3 hours to produce an isocyanate component "NCO-2" with an NCO% of 10.08%.

(Prepolymer: OH-R1)
In the blending ratio shown in Table 1, (1) bio-based liquid polyether polyol [H-2000] and (2) liquid polyether polyol [PPG-1000] were mixed uniformly at 60°C and stirred, and (4) 4,4'-diphenylmethane diisocyanate [MDI], which had been kept at 60°C, was added and stirred at 80°C for 2 hours. Then, (3) bio-based liquid chain extender [1,3PDO] was added and reacted at 80°C for 1 hour to produce an OH-type prepolymer "OH-R1" with an OHV of 71.60.

(Prepolymer: OH-R2)
In the proportions shown in Table 1, (7) liquid polycarbonate dipolyol [C-2090], (8) liquid polyester dipolyol [P-2010], and (9) liquid castor oil-based polyol [HS CM-025P] were mixed and stirred at 60°C, and (4) 4,4'-diphenylmethane diisocyanate [MDI], which had been kept at 60°C, was added and stirred at 80°C for 2 hours. Then, (3) bio-liquid chain extender [1,3PDO] was added and reacted at 80°C for 1 hour to produce an OH-type prepolymer "OH-R2" with an OHV of 96.99.

Next, Examples 1-5 and Comparative Example 1 of the two-component urethane resin composition for synthetic leather of this invention were produced using the raw materials (main component and NCO component including OH component, catalyst, and filler) and blending ratios (parts by mass) shown in Table 2 below, and synthetic leather for sports shoes was produced using Examples 1-5. The filler ( _CaCO3 ) used was a biofiller derived from eggshell powder.

The instantaneous mixer used in the examples and comparative examples is of a well-known structure, as described in Patent Document 1. It is a device that instantly and uniformly mixes liquids supplied to multi-stage impellers rotating at high speed inside a cylinder, and can then discharge the resulting mixture from a mixing head.

Table 2 lists the manufacturing conditions (composition of ingredients, temperature conditions, etc.) and the evaluation of the synthetic leather's physical properties. The evaluation of the synthetic leather's physical properties, "peel strength (kg/cm) and flexural durability at room temperature," was measured using a flexometer in accordance with the test method of JIS K6545.

[Example 1]
The polyol compound (OH-1a, liquid temperature 25°C) from Production Example 1 and a tertiary amine catalyst (SA1102, temperature-sensitive catalyst, manufactured by San-Apro Co., Ltd.) were mixed and stirred as the OH component to form the main component, to which NCO-2 (25°C) from Production Example 6 was added as the curing agent (NCO component), and the mixture was mixed and stirred using an instantaneous mixer, and applied to release paper with a skin for sports shoes at a rate of 400 g/ ^m2 using a roll coater (Comma Coater: registered trademark).

This was pre-dried for 2 minutes at 120°C to semi-harden it, then a separately prepared nonwoven fabric impregnated with a water-based polyurethane resin was placed on top of it and post-dried at 120°C for 10 minutes. The release paper was then peeled off to produce synthetic leather for sports shoes.

[Example 2]
The main component was a mixture of the polyol compound (OH-1a, liquid temperature 25°C) from Production Example 1 as the OH component, calcium carbonate (CaCO ₃ ) as the filler, and a tertiary amine catalyst (SA1102, temperature-sensitive catalyst, manufactured by San-Apro Co., Ltd.), and NCO-2 (25°C) from Production Example 6 was added as the curing agent (NCO component), and the mixture was mixed and stirred using an instantaneous mixer.The mixture was then applied at 400 g/m ² to release paper with a skin for sports shoes using a roll coater (Comma Coater: registered trademark).

This was pre-dried for 2 minutes at 120°C to semi-harden it, then a separately prepared nonwoven fabric impregnated with a water-based polyurethane resin was placed on top of it and post-dried for 9 minutes at 120°C. The release paper was then peeled off to produce synthetic leather for sports shoes.

[Example 3]
The polyol compound (OH-1b, liquid temperature 25°C) from Production Example 2 and a tertiary amine catalyst (SA1102, temperature-sensitive catalyst, manufactured by San-Apro Co., Ltd.) were mixed and stirred as the OH component to form the main component, to which NCO-2 (25°C) from Production Example 6 was added as the curing agent (NCO component), and the mixture was mixed and stirred using an instantaneous mixer, and 400 g/ ^m2 was applied to release paper with a skin for sports shoes using a roll coater (Comma Coater: registered trademark).

This was pre-dried for 2 minutes at 120°C to semi-harden it, then a separately prepared nonwoven fabric impregnated with water-based polyurethane resin was placed on top of it and post-dried for 7 minutes at 120°C. The release paper was then peeled off to produce synthetic leather for sports shoes.

[Example 4]
The polyol compound (OH-1b, liquid temperature 25°C) from Production Example 2 was mixed and stirred as the OH component, calcium carbonate (CaCO ₃ ) as a filler, and a tertiary amine catalyst (SA1102, temperature-sensitive catalyst, manufactured by San-Apro Co., Ltd.) to form the main component, and NCO-2 (25°C) from Production Example 6 was added as the curing agent (NCO component) and mixed and stirred using an instantaneous mixer. 400 g/m ² was applied to release paper using a roll coater (Comma Coater: registered trademark).

This was pre-dried for 2 minutes at 120°C to semi-harden it, then a separately prepared nonwoven fabric impregnated with a water-based polyurethane resin was placed on top of it and post-dried for 6 minutes at 120°C. The release paper was then peeled off to produce synthetic leather for sports shoes.

[Example 5]
The OH component was a mixture of the polyol compound of Production Example 1 (OH-1a, liquid temperature 25°C), calcium carbonate (CaCO ₃ ) as a filler, and a tertiary amine catalyst (San-Apro; SA1102, temperature-sensitive catalyst) as the main component, and carbodiimide-modified liquid MDI (Mitsui Chemicals; Cosmonate LL, NCO 29.0%) was added as the curing agent (NCO component) and mixed and stirred using an instantaneous mixer. 400 g/m ² was applied to release paper with a skin for sports shoes using a roll coater (Comma Coater: registered trademark).

This was pre-dried for 2 minutes at 120°C to semi-harden it, then a separately prepared nonwoven fabric impregnated with a water-based polyurethane resin was placed on top of it and post-dried for 5 minutes at 120°C. The release paper was then peeled off to produce synthetic leather for sports shoes.

[Comparative Example 1]
The OH component was prepared by mixing and stirring the above-mentioned (prepolymer: OH-R1, liquid temperature 50°C), tertiary amine catalyst (manufactured by Air Products; 33LV) and tertiary amine catalyst (manufactured by San-Apro; SA1102, temperature-sensitive catalyst) and used as the main component. NCO-2 (25°C) from Production Example 6 was added as the curing agent (NCO component), and the mixture was mixed and stirred using an instantaneous mixer, and 400 g/ ^m2 was applied to release paper using a roll coater (Comma Coater: registered trademark).

This was pre-dried for 2 minutes at 120 minutes to semi-harden it, then a separately prepared nonwoven fabric impregnated with a water-based polyurethane resin was placed on top of it and post-dried at 120°C for 98 minutes. The release paper was then peeled off to produce synthetic leather for sports shoes.

As is clear from the polyol components in Table 1 and the test results shown in Table 2, Examples 1 to 5, which used polyols containing 2 to 5% by mass of autocatalytic amine polyol (Production Examples 1 and 2), cured in 7 to 12 minutes at room temperature despite having a small amount of tertiary amine catalyst and a prepolymer component ratio of less than 50%. The resulting synthetic leather resin coating had a peel strength of 4.2 kg/cm or more, sufficient for sports shoes, and also demonstrated room-temperature flex durability of over 150,000 cycles. Based on these findings, Examples 1 to 5 were evaluated as two-component urethane resin compositions for synthetic leather that can be used with environmentally friendly raw materials and manufacturing conditions to produce high-quality synthetic leather that is sufficiently durable and practical for sports shoes.

Next, Examples 6-10 and Comparative Example 2 of the two-component urethane resin composition for synthetic leather of the present invention were produced using the blending ratios (parts by mass) of raw materials shown in Table 3 below, and further synthetic leather for automobiles or furniture was produced using Examples 6-10.
Table 3 also lists the manufacturing conditions (composition of ingredients, temperature conditions, etc.) and evaluation of the physical properties of the synthetic leather.

Among the evaluations of the physical properties of the synthetic leather, the "peel strength" and "room temperature flexibility" were obtained by the same test methods as those shown in Table 2.
The hydrolysis resistance test was carried out using the Jungle Test, in which synthetic leather test pieces were exposed to a high-temperature, high-humidity environment of 70°C and 95% humidity for four weeks. Those that showed no deterioration, were of good quality, and had a property retention rate of 80% or more were rated as good.

[Example 6]
The polyol compound (OH-2a, liquid temperature 25°C) of Production Example 3 and a tertiary amine catalyst (SA1102, temperature-sensitive catalyst, manufactured by San-Apro Co., Ltd.) were mixed and stirred as the OH component to form the main component, to which NCO-1 (25°C) of Production Example 5 was added as the curing agent (NCO component), and the mixture was mixed and stirred using an instantaneous mixer, and applied to automotive release paper with a surface at 250 g/ ^m2 using a roll coater (Comma Coater: registered trademark).

This was pre-dried for 2 minutes at 120°C to semi-harden, and then a knitted base fabric for automobiles was placed on top of it and post-dried for 7 minutes at 120°C. The release paper was then peeled off to produce synthetic leather for automobiles or furniture.

[Example 7]
The OH component was a mixture of the polyol compound (OH-2a, liquid temperature 25°C) from Production Example 3, calcium carbonate (CaCO ₃ ) as a filler, and a tertiary amine catalyst (SA1102, temperature-sensitive catalyst, manufactured by San-Apro Co., Ltd.), which was used as the main component. NCO-1 (25°C) from Production Example 5 was added as the curing agent (NCO component), and the mixture was mixed and stirred using an instantaneous mixer. 250 g/m ² was applied to automotive release paper with a skin using a roll coater (Comma Coater: registered trademark).

This was pre-dried for 2 minutes at 120°C to semi-harden it, then a separately prepared nonwoven fabric impregnated with water-based polyurethane resin was placed on top of it and post-dried for 6 minutes at 120°C. The release paper was then peeled off to produce synthetic leather for automobiles or furniture.

[Example 8]
The polyol compound (OH-2b, liquid temperature 25°C) from Production Example 4 and a tertiary amine catalyst (SA1102, temperature-sensitive catalyst, manufactured by San-Apro Co., Ltd.) were mixed and stirred as the OH component to form the main component, to which NCO-1 (25°C) from Production Example 5 was added as the curing agent (NCO component), and the mixture was mixed and stirred using an instantaneous mixer, and applied to automotive release paper with a surface at 400 g/ ^m2 using a roll coater (Comma Coater: registered trademark).

This was pre-dried for 2 minutes at 120°C to semi-harden it, then a separately prepared nonwoven fabric impregnated with water-based polyurethane resin was placed on top of it and post-dried for 5 minutes at 120°C. The release paper was then peeled off to produce synthetic leather for automobiles or furniture.

[Example 9]
The OH component was a mixture of the polyol compound (OH-2b, liquid temperature 25°C) from Production Example 4, calcium carbonate (CaCO ₃ ) as a filler, and a tertiary amine catalyst (SA1102, temperature-sensitive catalyst, manufactured by San-Apro Co., Ltd.), which was used as the main component. NCO-1 (25°C) from Production Example 5 was added as the curing agent (NCO component), and the mixture was mixed and stirred using an instantaneous mixer. 250 g/m ² was applied to automotive release paper with a skin using a roll coater (Comma Coater: registered trademark).

This was pre-dried for 2 minutes at 120°C to semi-harden it, then a separately prepared nonwoven fabric impregnated with water-based polyurethane resin was placed on top of it and post-dried for 5 minutes at 120°C. The release paper was then peeled off to produce synthetic leather for automobiles or furniture.

[Example 10]
The OH component was a mixture of the polyol compound of Production Example 3 (OH-2a, liquid temperature 25°C), calcium carbonate (CaCO ₃ ) as a filler, and a tertiary amine catalyst (SA1102, temperature-sensitive catalyst, manufactured by San-Apro Co., Ltd.), which was used as the main component. Carbodiimide-modified liquid MDI (Cosmonate LL, NCO 29.0%, manufactured by Mitsui Chemicals Co., Ltd.) was added as the curing agent (NCO component), and the mixture was mixed and stirred using an instantaneous mixer. 250 g/m ² was then applied to automotive surface release paper using a roll coater (Comma Coater: registered trademark).

This was pre-dried for 2 minutes at 120°C to semi-harden it, then a separately prepared nonwoven fabric impregnated with water-based polyurethane resin was placed on top of it and post-dried for 4 minutes at 120°C. The release paper was then peeled off to produce synthetic leather for automobiles or furniture.

[Comparative Example 2]
The OH component was prepared by mixing and stirring the above-mentioned (prepolymer: OH-R2, liquid temperature 50°C), tertiary amine catalyst (manufactured by Air Products; 33LV), and tertiary amine catalyst (manufactured by San-Apro; SA1102, temperature-sensitive catalyst) to form the main component. NCO-1 (25°C) from Production Example 5 was added as the curing agent (NCO component), and the mixture was mixed and stirred using an instantaneous mixer. The mixture was then applied to automotive surface release paper at a rate of 250 g/ ^m2 using a roll coater (Comma Coater: registered trademark).

This was pre-dried for 2 minutes at 120°C to semi-harden it, then a separately prepared nonwoven fabric impregnated with water-based polyurethane resin was placed on top of it and post-dried for 58 minutes at 120°C. The release paper was then peeled off to produce synthetic leather for automobiles or furniture.

As is clear from the polyol components in Table 1 and the test results shown in Table 3, Examples 6 to 10, which used polyols containing 2 to 3% by weight of an autocatalytic amine polyol (Production Examples 3 and 4), cured in 6 to 9 minutes at room temperature despite having a small amount of tertiary amine catalyst and a prepolymer component ratio of 35.0% or less. The resulting synthetic leather resin coating had a peel strength of 1.7 kg/cm or more, sufficient for synthetic leather for automobiles or furniture, and also demonstrated room-temperature flex durability of over 150,000 times. Based on these findings, Examples 6 to 10 were evaluated as two-component urethane resin compositions for synthetic leather that can be used to produce high-quality, durable synthetic leather for automobiles or furniture using environmentally friendly raw materials and manufacturing conditions.

The industrial applications of this invention extend beyond sports shoes to include general shoes, automobiles, furniture, bags, pouches, miscellaneous goods, clothing, industrial materials, and other synthetic leathers in general. By appropriately selecting and combining the polyols, chain extenders, and isocyanate compounds used in production, this invention can be used to produce high-quality synthetic leather for a variety of purposes.

Claims (7)

A two-component urethane resin composition for synthetic leather comprises a liquid base agent containing a polyol compound and a chain extender, and a liquid curing agent containing an isocyanate compound, wherein the polyol compound is a liquid polyol compound containing 1 to 15 mass% of an autocatalytic amine polyol containing two or more tertiary amine groups and three or more hydroxyl groups , based on 100 mass% of the polyol compound, and the prepolymer component ratio is less than 50% . The two-component urethane resin composition for synthetic leather according to claim 1, wherein the amine-based polyol is an amine-based polyether polyol having a hydroxyl value of 300 to 1,000 KOH mg/g, which is obtained by addition polymerization of propylene oxide (PO) or propylene oxide (PO) and ethylene oxide (EO) together with one or more amines selected from ethylenediamine, diethylenetriamine, toluenediamine, and tetraethylenepentamine. The two-component urethane resin composition for synthetic leather according to claim 1 or 2, wherein the base agent contains a biopolyol, a biochain extender, or both. The two-component urethane resin composition for synthetic leather according to claim 1 or 2, wherein the equivalent ratio (isocyanate group/hydroxyl group) of the two-component urethane resin composition is 1.0 to 1.4. The two-component urethane resin composition for synthetic leather according to claim 3, wherein the equivalent ratio (isocyanate group/hydroxyl group) of the two-component urethane resin composition is 1.0 to 1.4. Synthetic leather having a base fabric surface coated with the two-component urethane resin composition for synthetic leather described in claim 1 or 2. Synthetic leather having a base fabric surface coated with the two-component urethane resin composition for synthetic leather described in claim 3.