JP6582515B2 - Polyurethane resin and leather adhesive using the composition - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a polyurethane resin composition useful for electronic device members such as communication tablets, clothing, furniture / household appliance members, daily goods, and automobile members, and a leather adhesive using the composition.

  Polyurethane resin is excellent in various physical properties such as wear resistance, flexibility, flexibility, flexibility, workability, adhesion, chemical resistance, etc., and is excellent in suitability for various processing methods. Widely used as resin components such as coating materials, inks, adhesives, paints, etc. for clothing, furniture / home appliances, household goods, architecture / civil engineering, and automobile parts, or as various molded articles such as films and sheets.

  Synthetic leather obtained by a dry method has been widely used in the fields of clothing, bags, bags, footwear, and the like because its appearance and texture are similar to natural leather. For example, as a method for producing a leather sheet, it has been proposed to use polyurethane obtained from 4,4'-diphenylmethane diisocyanate and polyether and 4,4'-diaminodiphenylmethane (see Patent Document 1). In order to improve the solubility of the polyurethane resin, a urethane resin composition containing an isomer other than 4,4'-diphenylmethane diisocyanate has been proposed (see Patent Document 2). It has also been proposed to use a specific polycarbonate diol in order to achieve both soft texture and durability such as heat resistance and water resistance (see Patent Documents 3 and 4).

Japanese Patent Publication No. 4-80141 Japanese Patent Laid-Open No. 10-8383 JP-A-5-51428 JP 2004-346094 A

  However, when used in contact with the human body for a long period of time, the sebum component contained in sweat or the oleic acid component contained in the skin protection cream may cause deterioration of the surface of the molded body and the phenomenon of stickiness. There was a fear that it could not be used.

  The present invention has been made in view of the background art as described above, and an object thereof is a polyurethane resin composition capable of achieving both chemical resistance to oleic acid and the like, durability and flexible texture, and the same. It is providing the adhesive composition using this.

  As a result of intensive studies to solve the above problems, the present inventors have found that a urethane resin using a specific polycarbonate diol and a specific isocyanate compound as a polyol component solves the above problems, and It came to be completed.

  That is, the present invention is as follows.

[1] A polyurethane resin obtained using at least a polycarbonate diol (A), a chain extender (B), and an isocyanate compound (C),
The polycarbonate diol (A) contains a carbonate component and a glycol component, and the glycol component has only a structural unit derived from a linear glycol having 3 to 10 carbon atoms, and the isocyanate compound (C) is 2, 2 4,4'-diphenylmethane, comprising 2,4'-diphenylmethane diisocyanate and 4,4'-diphenylmethane diisocyanate, and the total amount of 2,2'-diphenylmethane diisocyanate and 2,4'-diphenylmethane diisocyanate A polyurethane resin characterized in that the ratio to the diisocyanate content is 40/60 to 70/30 (mass ratio).

  [2] The polyurethane resin as described in [1] above, wherein the polycarbonate diol (A) has a number average molecular weight of 2,000 to 5,000.

  [3] A polyurethane resin, wherein the polyurethane resin according to any one of [1] or [2] has a number average molecular weight of 40,000 or more.

  [4] A composition for an adhesive comprising the polyurethane resin according to any one of [1] to [3] above and a polyisocyanate curing agent.

  [5] A leather adhesive using the adhesive composition according to [4].

  The polyurethane resin composition of the present invention can achieve both chemical resistance and durability against oleic acid and a soft texture.

  And, by using the polyurethane resin composition of the present invention for an adhesive composition, particularly an adhesive for leather, chemical resistance and durability to oleic acid and the like, which could not be achieved conventionally, have a flexible texture. At the same time, various properties such as wear resistance, scratch resistance, water resistance, stain resistance, weather resistance, and adhesiveness can be imparted.

  Hereinafter, the present invention will be described in detail.

The present invention is a polyurethane resin obtained using at least a polycarbonate diol (A), a chain extender (B), and an isocyanate compound (C),
The polycarbonate diol (A) contains a carbonate component and a glycol component, and the glycol component has only a structural unit derived from a linear glycol having 3 to 10 carbon atoms, and the isocyanate compound (C) is 2, 2 4,4'-diphenylmethane, comprising 2,4'-diphenylmethane diisocyanate and 4,4'-diphenylmethane diisocyanate, and the total amount of 2,2'-diphenylmethane diisocyanate and 2,4'-diphenylmethane diisocyanate The ratio with respect to the content of diisocyanate is 40/60 to 70/30 (mass ratio).

  In the present invention, the polycarbonate diol (A) has a polymer chain in which a hydrocarbon group derived from a polyol is connected via a carbonate bond, and a hydroxyl group bonded to both ends of the polymer chain. And having the following repeating structural unit (a). N in the following formula is 3-10.

  The polycarbonate diol (A) used in the present invention contains a carbonate component and a glycol component. For example, dialkyl carbonates such as dimethyl carbonate and diethyl carbonate, alkylene carbonates such as ethylene carbonate and propylene carbonate, diphenyl carbonate, dinaphthyl carbonate, It can be obtained by reacting carbonates such as diaryl carbonates such as dianthryl carbonate, diphenanthryl carbonate, diindanyl carbonate, and tetrahydronaphthyl carbonate with a linear glycol having 3 to 10 carbon atoms.

  Although it does not specifically limit as a C3-C10 linear glycol in this invention, For example, 1, 3- propylene glycol, 1, 4- butane diol, 1, 5- pentane diol, 1, 6-, Examples include hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol. These may be used alone or in combination of two or more. Considering availability, chemical resistance, and peel strength, 1,6-hexanediol is optimal.

  In the present invention, the number average molecular weight of the polycarbonate diol (A) is preferably in the range of 2,000 to 5,000, more preferably 2,000, considering flexibility, ease of synthesis, and ease of handling. It is in the range of ~ 3,000.

  In the present invention, the chain extender (B) is not particularly limited, and examples thereof include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,3. -Butanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,4-bis (β-hydroxyethoxy) benzene, neopentyl glycol, methyloctanediol, 1,9-nonanediol, Bisphenol, cyclohexane dimethanol, dimethylol heptane, polypropylene glycol, etc. are mentioned. Further, 1,4-butanediol can be suitably used from the balance of flexibility and durability.

  The use ratio of the polycarbonate diol (A) and the chain extender (B) is preferably 0.05 to 7, more preferably 0.1 to 5, particularly preferably as the molar ratio (B) / (A). Is 0.2-4.

  The isocyanate compound (C) in the present invention is diphenylmethane diisocyanate (hereinafter abbreviated as MDI) diisocyanate and includes 2,2'-MDI, 2,4'-MDI, and 4,4'-MDI. The MDI diisocyanate in the present invention is a ratio of the total amount of 2,2′-MDI and 2,4′-MDI to the content of 4,4′-MDI ([2,2′-MDI and 2,4′- MDI total amount] / [4,4′-MDI content]) is 40/60 to 70/30 (mass ratio). When this ratio is higher than 70/30 (mass ratio), the oleic acid resistance decreases. Moreover, when this ratio is lower than 40/60 (mass ratio), in addition to insufficient flexibility, the resin viscosity increases and the peel strength decreases.

  The polyurethane resin obtained in the present invention preferably has a number average molecular weight of 40,000 or more, more preferably 40,000 to 90,000. If the number average molecular weight is less than the lower limit, the flexibility and elongation of the cured film formed from the resin tends to be insufficient, which is not preferable.

  The polyurethane resin in the present invention can be produced, for example, by putting the above-described components (A) to (C) into an organic solvent and allowing them to react.

  Here, the reaction temperature is usually preferably in the range of 20 to 100 ° C. The reaction may be carried out as appropriate until the isocyanate residue disappears, and the reaction time of the urethanization reaction varies depending on the presence / absence, type and temperature of the catalyst, but is generally within 10 hours, preferably 1 to 5 hours is sufficient. It is. In addition, problems such as coloring may occur as the reaction time increases.

  As the organic solvent used for the production of the polyurethane resin composition, a solvent that does not affect the urethanization reaction is appropriately selected. Specific examples of the organic solvent include aliphatic hydrocarbons such as octane, alicyclic hydrocarbons such as cyclohexane and methylcyclohexane, ketones such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, ethyl acetate, butyl acetate, and isobutyl acetate. Esters such as ethylene glycol ethyl ether acetate, propylene glycol monomethyl ether acetate, 3-methyl-3-methoxybutyl acetate, glycol ether esters such as ethyl-3-ethoxypropionate, ethers such as dioxane, iodination Polarized aprotic such as halogenated hydrocarbons such as methylene and monochlorobenzene, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, dimethylsulfoxide, hexamethylphosphonylamide Medium, and the like. These solvents can be used alone or in combination of two or more.

  This urethanization reaction proceeds even without a catalyst, but a known urethanization reaction catalyst can be used to accelerate the reaction. Specific examples of catalysts that can be used in the urethanization reaction include the use of organic metal compounds such as dibutyltin diacetate, dibutyltin dilaurate, dioctyltin dilaurate, organic amines such as triethylenediamine and triethylamine, and salts thereof. it can.

  In the polyurethane resin composition of the present invention, if necessary, for example, an antioxidant, an ultraviolet absorber, a pigment, a dye, a solvent, a flame retardant, a hydrolysis inhibitor, a lubricant, a plasticizer, a filler, an antistatic agent. Additives such as an agent, a dispersant, a catalyst, a storage stabilizer, a surfactant, and a leveling agent can be appropriately blended.

  In the present invention, the viscosity of the polyurethane resin composition is not particularly limited, but is preferably 1,000 to 25,000 mPa · s at 25 ° C., more preferably 1,000 to 20,000 mPa · s. s. When the upper limit is exceeded, the workability is lowered and the peel strength is lowered. In adjusting the viscosity, the organic solvent can be used for dilution.

  The polyurethane resin composition of the present invention is a resin component such as a coating material, ink, adhesive, paint, etc. for electronic equipment members, clothing, furniture / home appliances, daily goods, construction / civil engineering, and automotive parts, or films, sheets. It can use suitably for various molded objects, such as. The application method of the resin composition is not particularly limited, and may be appropriately selected from known methods. Moreover, what is necessary is just to make an application quantity and the thickness of a coating film appropriate according to the material etc. of a to-be-coated surface.

  The coating film formed using the polyurethane resin composition of the present invention is suitably used for various applications where flexibility and oleic acid resistance are required for the formed cured film.

  The composition for adhesives of the present invention contains the above-described polyurethane resin of the present invention and a polyisocyanate curing agent.

  Specific examples of the polyisocyanate curing agent used in combination with the polyurethane resin of the present invention include aromatic diisocyanate, aliphatic diisocyanate, alicyclic diisocyanate, araliphatic diisocyanate, and these polyisocyanates as long as the performance does not deteriorate. Isocyanurate group-containing polyisocyanate, uretdione group-containing polyisocyanate obtained as a raw material, uretdione group and isocyanurate group-containing polyisocyanate, urethane group-containing polyisocyanate, allophanate group-containing polyisocyanate, burette group-containing polyisocyanate, uretonimine group-containing polyisocyanate Etc. can also be used.

  The adhesive composition of the present invention has both chemical resistance and durability against oleic acid and a soft texture, and wear resistance, scratch resistance, water resistance, stain resistance, weather resistance, and adhesiveness. In particular, it is suitably used as an adhesive for leather.

[Production of polyol compound 1]
Blending 1,6-hexanediol (hereinafter abbreviated as 1,6-HG) as a glycol with diethyl carbonate (hereinafter abbreviated as DEC) in a reaction apparatus including a stirrer, a thermometer, a heating device, and a distillation tower. While charging 830 g of 1,6-HG and 771 g of DEC so that the ratio is 1.08 in molar ratio, 0.05 g of tetrabutyl titanate (hereinafter abbreviated as TBT) is further charged as a reaction catalyst under a nitrogen stream. The temperature was gradually raised to 190 ° C. When the distillation of ethanol slows down and the top temperature of the distillation column becomes 50 ° C. or lower, the pressure is gradually reduced to 1.3 kPa while maintaining the reaction temperature at 190 ° C., and further at a pressure of 1.3 kPa for 7 hours. Reacted. Furthermore, the reaction was continued under a reduced pressure of 1.3 kPa or less at a reaction temperature of 190 ° C. until the hydroxyl value of the reaction product became 54 to 58 (mg-KOH / g) to obtain a polyol compound (Polyol-1). The obtained polycarbonate diol had a hydroxyl value of 55.6 (mg-KOH / g).

[Manufacture of polyol compound 2]
In the same production method as in Production 1 of polyol compound, the reaction mixture was synthesized in the same manner except that 826 g of 1,6-HG and 787 g of DEC were charged so that the molar ratio was 1.05. The reaction was continued until the value was 35 to 39 (mg-KOH / g) to obtain a polyol compound (Polyol-2). The obtained polycarbonate diol had a hydroxyl value of 37.3 (mg-KOH / g).

[Manufacture of polyol compound 3]
In the production method similar to the production 1 of the polyol compound, a hydroxyl group of the reaction product was synthesized by the same method except that 841 g of 1,6-HG and 723 g of DEC were added so that the mixing ratio was 1.16 in molar ratio. The reaction was continued until the value became 110 to 114 (mg-KOH / g) to obtain a polyol compound (Polyol-3). The obtained polycarbonate diol had a hydroxyl value of 112.2 (mg-KOH / g).

[Production of polyol compound 4]
In the production method similar to the production 1 of the polyol compound, 3-methyl-1,5-pentanediol / 1,6-HG = 9/1 (molar ratio), and the blending ratio with respect to DEC is 1.08 in molar ratio. In this way, synthesis is performed in the same manner except that 747 g of MPD, 83.0 g of 1,6-HG, and 771 g of DEC are charged, and the reaction product has a hydroxyl value of 54 to 58 (mg-KOH / g). The reaction was continued to obtain a polyol compound (Polyol-4). The obtained polycarbonate diol had a hydroxyl value of 56.0 (mg-KOH / g).

  In the following comparative examples, Placel-5 (manufactured by Daicel Corporation) (polycaprolactone diol, hydroxyl value 56.1 mg-KOH / g) was used as Polyol-5. Further, as Polyol-6, PTG-2000SN (polytetramethylene glycol, hydroxyl value 56.1 mg-KOH / g) manufactured by Hodogaya Chemical Co., Ltd. was used.

  In addition, the raw materials used in the present invention are shown below.

MDI-1: 2,2′-MDI + 2,4′-MDI = 1.8%, 4,4′-MDI = 98.2%.
MDI-2: 2,2′-MDI + 2,4′-MDI = 93.0%, 4,4′-MDI = 7.0%.
1,4-BG: 1,4-butanediol manufactured by Mitsubishi Chemical.
Neostan U-600: Urethane catalyst Made by Nitto Kasei.
Example 1.
[Synthesis of polyurethane resin]
A 2-liter four-necked flask equipped with a stirrer, a thermometer, a heating device, and a distillation tower was charged with 257 g of Polyol-1, 2.9 g of 1,4-BG, and methyl ethyl ketone (hereinafter referred to as MEK). 298.7 g) was charged, and nitrogen gas was bubbled with uniform stirring at 45 ° C. to prepare a polymer polyol solution. This polymer polyol solution was charged with 22.4 g of MDI-1 and 16.1 g of MDI-2 and subjected to urethanization reaction at 70 ° C. for 4 hours in a nitrogen stream. Upon completion of the reaction, it was confirmed by the infrared absorption spectrum that no isocyanate residue was observed. Thereafter, 401.3 g of MEK was added and mixed at 50 ° C. for 1 hour. In this way, a resin solution containing 30% by mass of a number average molecular weight of 60,000 and a urethane resin as a solid content was obtained.

<GPC: Measurement of molecular weight>
(1) Measuring instrument: HLC-8220 (manufactured by Tosoh Corporation)
(2) Column: TSKgel (manufactured by Tosoh Corporation)
・ G3000H-XL
・ G2500H-XL
・ G2000H-XL, G1000H-XL
(3) Carrier: THF (tetrahydrofuran)
(4) Detector: RI (refractive index) detector (5) Temperature: 40 ° C
(6) Flow rate: 1.000 ml / min
(7) Calibration curve: Standard polystyrene (manufactured by Tosoh Corporation)
F-80 (molecular weight: 7.06 × 10 ⁵ , molecular weight distribution: 1.05)
F-20 (molecular weight: 1.90 × 10 ⁵ , molecular weight distribution: 1.05)
F-10 (molecular weight: 9.64 × 10 ⁴ , molecular weight distribution: 1.01)
F-2 (molecular weight: 1.81 × 10 ⁴ , molecular weight distribution: 1.01)
F-1 (molecular weight: 1.02 × 10 ⁴ , molecular weight distribution: 1.02)
A-5000 (molecular weight: 5.97 × 10 ³ , molecular weight distribution: 1.02)
A-2500 (molecular weight: 2.63 × 10 ³ , molecular weight distribution: 1.05)
A-500 (molecular weight: 5.0 × 10 ² , molecular weight distribution: 1.14)
(8) Sample solution concentration: 0.5% THF solution.

[Synthesis of other polyurethane resins]
In the same manner as in the production of the polyurethane resin of Example 1, with the charged composition (blending amount; mass) of each raw material as described in Table 1, Examples 2 to 6 and Comparative Examples 1 to 1 listed in Table 1 were used. The polyurethane resin of each sample of 5 was synthesized.

[Creation of film using polyurethane resin solution]
A resin composition was prepared by adding 5 parts by mass of a crosslinking agent (Coronate L manufactured by Tosoh Corporation) to 100 parts by mass of the obtained polyurethane resin solution. The resin composition was applied onto a release paper so that the dry film pressure was 100 μm, left at room temperature for 20 minutes, then heat-treated in a dryer at a temperature of 60 ° C. for 20 minutes, and at 120 ° C. for 20 minutes, Thereafter, the cured film was produced by curing at 40 ° C. for 24 hours. Using this cured product, physical properties were evaluated.

〔Evaluation methods〕
The tensile properties of the obtained test piece were measured according to JIS K7311.
Test apparatus: Tensilon UTA-500 (manufactured by A & D)
-Measurement conditions: 25 ° C x 50% RH
Head speed: 200 mm / min Dumbbell: No. 4.

(1) Film tensile property test 100% modulus: Tensile stress at 100% elongation.
Tensile strength at break: Maximum stress until the specimen breaks.
Elongation: Elongation ratio of the distance between marked lines when the specimen is broken.

(2) Flexibility In the evaluation, “◯” indicates that the elongation at break in the tensile properties is 400% or more, “Δ” indicates that the elongation is 250% or more and less than 400%, and “x” indicates that the elongation is less than 250%.

(3) Water resistance The obtained test piece was similarly allowed to stand at 50 ° C./95% RH for 500 hours, and the tensile strength retention rate (%) from the initial value was measured. A sample having a retention rate of 80% or more was indicated by “◯”, and a sample having a retention rate lower than that was indicated by “X”.

(4) Heat resistance The obtained test piece was similarly allowed to stand at 90 ° C. for 500 hours, and the tensile strength retention (%) from the initial value was measured. A sample having a retention rate of 80% or more was indicated by “◯”, and a sample having a retention rate lower than that was indicated by “X”.

(5) Oleic acid resistance The coating film was coated with 10 g / m ² of oleic acid, covered with aluminum foil, allowed to stand at 80 ° C. for 24 hours, and then the wiped appearance was visually evaluated.

<Evaluation criteria>
-Most of the coating film is swollen, wrinkled or dissolved (evaluation: x)
・ Slightly blistered coating film (Evaluation: ○)
・ No change in coating film (evaluation: A).

[Peel strength evaluation method]
A resin composition was prepared by adding 5 parts by mass of a crosslinking agent (Coronate L manufactured by Tosoh Corporation) to 100 parts by mass of the polyurethane resin solution. An adhesive prepared on a polyurethane film having a thickness of about 45 μm was applied after drying so as to have a film thickness of 50 μm, and preliminarily dried at 80 ° C. for 30 seconds. Thereafter, the base fabric was bonded and pressure-bonded with a roller, and cured at 70 ° C. for 12 hours and at room temperature for 24 hours to obtain a synthetic leather.

  The peel strength of the obtained leather was measured according to JIS K6772.

Test apparatus: Tensilon UTA-500 (manufactured by A & D).
Measurement conditions: 25 ° C. × 50% RH.
-Head speed: 200 mm / min.

  For the adhesiveness, those having a peel strength of 5 N / cm or more were “◯”, and those having a peel strength of less than 5 N / cm were “x”.

Claims (5)

A polyurethane resin solution obtained using at least a polycarbonate diol (A), a chain extender (B), and an isocyanate compound (C),
The polycarbonate diol (A) contains a carbonate component and a glycol component, and has only 1,6-hexanediol as a structural unit as a glycol component,
The isocyanate compound (C) contains 2,2′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, and 4,4′-diphenylmethane diisocyanate, and 2,2′-diphenylmethane diisocyanate and 2,4′-diphenylmethane diisocyanate The ratio of the total amount of 4,4′-diphenylmethane diisocyanate is 40/60 to 70/30 (mass ratio),
And containing an organic solvent,
A polyurethane resin solution characterized by The number average molecular weight of polycarbonate diol (A) is 2,000-5,000, The polyurethane resin solution of Claim 1 characterized by the above-mentioned. 3. A polyurethane resin solution , wherein the polyurethane resin according to claim 1 has a number average molecular weight of 40,000 or more. An adhesive composition comprising the polyurethane resin solution according to any one of claims 1 to 3 and a polyisocyanate curing agent. A leather adhesive using the adhesive composition according to claim 4.