JPH07165856A - Production of polyurethane resin and polyurethane resin composition - Google Patents

Abstract

PURPOSE:To produce a polyurethane resin having light yellowing resistance, NOx gas yellowing resistance, and heat resistance. CONSTITUTION:This production process comprises reacting a polymer diol with an aromatic diisocyanate in an equivalent ratio of 1: (1.3-5.) to obtain an isocyanate-terminated prepolymer, extending the chain of the prepolymer with 40-80 equivalent %, based on the isocyanate groups of the prepolymer, aromatic diamine, and completing the chain extension by adding 90-110 equivalent %, based on the isocyanate groups of the obtained polymer, low-molecular diol to the reaction system.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a polyurethane resin. More specifically, light yellowing resistance and N resistance
The present invention relates to a method for producing a polyurethane resin for artificial leather and synthetic leather, which is excellent in Ox gas yellowing and also excellent in heat resistance, and a polyurethane resin composition.

[0002]

2. Description of the Related Art Conventionally, when a polymer diol is reacted with an organic diisocyanate and a chain extender to produce a polyurethane resin, ethylene glycol is used as a chain extender.
Those using low-molecular diols such as 1,4-butanediol had a low thermal softening point and poor heat resistance. Further, in the case of using an aromatic diamine such as 2,4- and / or 2,6-tolylenediamine or 4,4'-diaminodiphenylmethane as a chain extender, a trace amount of free aromatic amine remains in the polyurethane resin. It was easily inferior to light yellowing resistance and NOx gas yellowing resistance. Various methods have been proposed to solve these problems, for example,
There is a method of using hexamethylene diisocyanate in a certain amount or more (JP-A-49-73496). The polyurethane resin obtained by this method is excellent in light yellowing resistance and NOx gas yellowing resistance but has a low thermal softening point. It was inferior in heat resistance. Further, a method of first subjecting a terminal isocyanate prepolymer from polydipropylene adipate diol and an organic diisocyanate to a chain extension reaction with a low-molecular diol and then completing the chain extension reaction with 1,2-propylenediamine (Japanese Patent Publication No. 56-39806). However, the polyurethane resin obtained by this method has good heat resistance, but is inferior in light yellowing resistance and NOx gas yellowing resistance.

[0003]

Thus, in order to produce a polyurethane resin satisfying light yellowing resistance and NOx gas yellowing resistance, an alicyclic diisocyanate is used and a low molecular diol is used as a chain extender. Those obtained have a low thermal softening point and inferior heat resistance. Further, in the case where an organic diamine (particularly aromatic diamine) is used as a chain extender in order to increase heat resistance, free aromatic amine is apt to remain in the polyurethane resin, resulting in light yellowing resistance and NOx resistance.
It is inferior to gas yellowing. That is, it has been difficult to manufacture a polyurethane resin for artificial leather and synthetic leather having both light yellowing resistance and NOx gas yellowing resistance and heat resistance by the conventional manufacturing method.

[0004]

[Means for Solving the Problems] The inventors of the present invention have made extensive studies to obtain a polyurethane resin which is excellent in light yellowing resistance and NOx gas yellowing resistance and is also excellent in heat resistance.

That is, the present invention relates to a method for producing a polyurethane resin by reacting a terminal isocyanate prepolymer obtained by reacting a polymeric diol with an organic diisocyanate with a chain extender, wherein (step 1) the polymeric diol (A ) And an aromatic diisocyanate (B) at an equivalent ratio of 1: 1.3 to 1: 5.0 to form a terminal isocyanate prepolymer (hereinafter abbreviated as prepolymer); (Step 2) step A step of carrying out a first stage chain extension reaction with an aromatic diamine (extending agent I) in an amount of 40 to 80% by weight based on the isocyanate group (hereinafter abbreviated as NCO group) of the prepolymer obtained in 1; 3) a step of completing the chain extension reaction with 90 to 110% of an equivalent low molecular weight diol (extender II) with respect to the NCO groups of the polymer obtained in step 2. A method for producing a polyurethane resin, characterized and.

As the polymer diol (A) used in (Step 1), for example, polyester diol [polyethylene adipate, polybutylene adipate, polycaprolactone diol, etc.], polyether diol [polyoxyethylene ether diol, polyoxy Propylene ether diol, polyoxytetramethylene ether diol, etc.], polyether ester diol [polyoxyethylene ether adipate, polyoxypropylene ether adipate, etc.] polycarbonate diol [polyhexamethylene carbonate diol, etc.], polydimethylsiloxane diol and these And a mixture of two or more thereof. The number average molecular weight of the polymer diol (A) is usually 500 to 5,000, preferably 800 to 3,000.

As the aromatic diisocyanate (B) used in (Step 1), for example, 2,4- and / or 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, p-Phenylene diisocyanate and mixtures of two or more thereof. Of these, preferred is 4,4'-diphenylmethane diisocyanate.

In step (1), the equivalent ratio of (A) and (B) when reacting (A) and (B) to form a prepolymer is usually 1: (1.3-5. 0), preferably 1: (1.5 to 4.0).

If the equivalent ratio of (B) is less than 1.3, the strength of the resulting polyurethane resin will be insufficient, and if it exceeds 5.0, the resulting polyurethane resin will be rigid, making it suitable for artificial leather and synthetic leather. When used, the artificial leather and synthetic leather obtained have a hard texture.

The aromatic diamine (extending agent I) in (Step 2) is, for example, 2,4- and / or 2,6.
-Tolylenediamine, 4,4'-diaminodiphenylmethane, 3,3'-dichloro-4,4'-diaminodiphenylmethane, 3,3'- and / or 4,4'-diaminodiphenylsulfone, 4,4'- Methylene-bis-
(2,6-diethylamine), 4,4′-methylene-bis- (2,6-diisopropylamine), 4,4′-methylene-bis- (3-chloro-2,6-diethylamine) and these 2 Mixtures of more than one species are mentioned. Among these, 4,4'-diaminodiphenylmethane is preferable.

The amount of the (stretching agent I) used is usually 40 to 8 relative to the NCO group of the prepolymer obtained in (Step 1).
It is 0% equivalent, preferably 50 to 70% equivalent. If the amount of the (stretching agent I) used is less than 40% equivalent, the heat softening point of the obtained polyurethane resin will be low, and the heat resistance will be poor. On the other hand, when it exceeds 80% by weight, free aromatic amine is likely to remain in the obtained polyurethane resin, resulting in poor light yellowing resistance and NOx gas yellowing resistance.

Examples of the low molecular weight diol (extending agent II) in (Step 3) include ethylene glycol, diethylene ether glycol, 1,3- and / or 1,
4-butanediol, 1,6-hexanediol, 1,
4-cyclohexanedimethanol, meta and / or paraxylylene glycol, neopentyl glycol,
1,4-bis (β-hydroxyethoxy) benzene, alkylene oxide adducts of bisphenol, and mixtures of two or more thereof. Of these, preferred are ethylene glycol and 1,4-butanediol.

The amount of the (extending agent II) to be used is usually 90 to 110% equivalent, preferably 90 to 110% by weight, based on the NC0 group of the prepolymer after the chain extension reaction of the first step by the above-mentioned (extending agent I). It is 95 to 105% equivalent. When the amount of (extendant II) used is less than 90% equivalent or more than 110% equivalent,
The degree of polymerization of the polyurethane resin does not increase, and a polyurethane resin having sufficient strength cannot be obtained.

Further, in the present invention, conventionally known polymerization terminators [alcohol-type polymerization terminators (methanol, ethanol, etc.); amine-type polymerization terminators (isopropylamine,
n-butylamine, di-n-butylamine, etc.), etc.]
May be used.

Next, the production of the polyurethane resin by the method of the present invention can be carried out in the presence or absence of a solvent, and (step 1) is carried out in the absence of a solvent, (step 2) and (step 3). Is preferably carried out in the presence of a solvent. Examples of the solvent when the solvent is used include amide solvents [dimethylformamide, dimethylacetamide, etc.]; sulfoxide solvents [dimethylsulfoxide, etc.]; ketone solvents [methylethylketone, cyclohexanone, etc.];
Examples thereof include ether solvents [dioxane, tetrahydrofuran, etc.]; ester solvents [ethyl acetate, etc.]; aromatic hydrocarbon solvents [toluene, xylene, etc.] and mixtures of two or more thereof. Among these, preferred are amide solvents and ketone solvents, and particularly preferred are amide solvents.

In the present invention, the reaction temperature in producing the polyurethane resin is usually 20 to 1 when a solvent is used.
The temperature is 20 ° C, preferably 30 to 100 ° C, and usually 20 to 220 ° C, preferably 50 to 170 ° C in the case of no solvent.

In order to accelerate the reaction, it is possible to use a known catalyst which is usually used in the polyurethane-forming reaction, if necessary, such as amine-based catalysts (triethylamine, triethylenediamine, etc.) and tin-based catalysts (dibutyltin dilaurate, etc.). it can.

In the polyurethane resin according to the present invention, other polymers (polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, etc.), additives (surfactant) may be added, if necessary, within a range that does not impair the performance of the product. Agent, pigment, weather resistance stabilizer, UV absorber, antioxidant, etc.) may be added.

The polyurethane resin obtained by the method of the present invention is excellent in light yellowing resistance and NOx gas yellowing resistance and is excellent in heat resistance. Therefore, it is particularly suitable for use in artificial leather, synthetic leather and the like.

[0020]

EXAMPLES The present invention will be further described below with reference to examples, but the present invention is not limited thereto. In the following, “part” means part by weight and “%” means% by weight.

The abbreviations of the compounds used are as follows. PTMG: polyoxytetramethylene ether diol having a number average molecular weight of 2000 MDI: 4,4'-diphenylmethane diisocyanate TDI: 2,6-tolylene diisocyanate IPDI: isophorone diisocyanate DAM: 4,4'-diaminodiphenylmethane HMDA: 1,6- Hexamethylenediamine DMF: Dimethylformamide EG: Ethylene glycol

The performance evaluation was carried out by the following method. (1) Light-resistant yellowing Polyurethane resin film (thickness: approx. 100μ) faded on meter (black panel temperature 63 ± 3 ° C) 1
The degree of yellowing of the polyurethane film after irradiation for 00 hours was evaluated on a gray scale (for contamination), and grade 4 or higher was rated as good and grade 4 or less was rated as poor. (2) Yellowing resistance to NOx gas According to JIS L-0855, the yellowing after exposure of 2 units of a polyurethane resin film was evaluated on a gray scale (for contamination), and grade 4 or higher was good and grade 4 or less was bad. did. (3) Heat resistance The thermal softening point of the polyurethane resin was measured using a thermal analysis system "TAS100" manufactured by Rigaku Denki Co., Ltd.
A temperature equal to or higher than 0 ° C was considered good, and a temperature lower than 200 ° C was regarded as poor.

Example 1 A four-necked flask was charged with 200 parts of PTMG and 75 parts of MDI and reacted at 100 ° C. for 2 hours in a dry nitrogen atmosphere (step 1). Then, 650 parts of DMF were charged to make the system uniform. At this time, the NCO group content in the solid content (hereinafter, NCO%
Abbreviated) was 6.1%. After setting the system temperature to 50 ° C., a previously prepared 30% DMF solution of DAM was added to 92.3.
Part (70% equivalent to NCO group of prepolymer after completion of (step 1)) was charged, and chain extension reaction was carried out at 50 ° C. for 3 hours (step 2). At this time, NCO% was 1.66%. Then, 3.7 parts of EG [(100% equivalent to the NCO group of the polymer after completion of (step 2)] was charged, and the temperature was 70 ° C.
The chain extension reaction is performed for 4 hours (step 3), and the resin concentration is 30
%, A polyurethane resin solution having a viscosity of 1100 poise (20 ° C.) was obtained.

Example 2 200 parts of PTMG, 75 parts of MDI, 659 of DMF
Part, 66 parts of a 30% DMF solution of DAM [50% equivalent to NCO group of prepolymer after completion of (step 1)],
6.2 parts of EG [(NCO of polymer after completion of (step 2)]
100% equivalent with respect to the base] and in the same manner as in Example 1 except that the resin concentration was 30% and the viscosity was 950 poise (20
A polyurethane resin solution (° C.) Was obtained.

Example 3 200 parts of PTMG, 52 parts of TDI, 597 of DMF
Parts, DAM 30% DMF solution 92.3 parts [70% equivalent to NCO groups of prepolymer after (step 1) completion], EG 3.7 parts [(step 2) after polymer Example 1 except that 100% equivalent to NCO group] was used.
A polyurethane resin having a resin concentration of 30% and a viscosity of 1050 poise (20 ° C.) was obtained in the same manner as in (1).

Comparative Example 1 200 parts of PTMG and 75 parts of MDI were charged in a four-necked flask, reacted at 100 ° C. for 2 hours in a dry nitrogen atmosphere, and then 642 parts of DMF were homogenized. At this time, NCO% was 6.1%. After the system temperature was set to 50 ° C, 125 parts of a 30% DMF solution of DAM prepared in advance (95% equivalent to NCO group of prepolymer) was charged, and chain extension reaction was performed at 50 ° C for 4 hours to obtain a resin concentration. Thirty
%, A viscosity of 1150 poise (20 ° C.) was obtained as a polyurethane resin solution.

Comparative Example 2 200 parts of PTMG and 75 parts of MDI were charged into a four-necked flask, reacted at 100 ° C. for 2 hours in a dry nitrogen atmosphere, and then 642 parts of DMF were charged to homogeneity in the system. At this time, NCO% was 6.1%. After adjusting the system temperature to 50 ° C, 12.4 parts of EG (100% equivalent to the NCO group of the prepolymer) was charged, and chain extension reaction was carried out at 70 ° C for 5 hours to give a resin concentration of 30% and a viscosity of 1150 poises. (20 ° C)
A polyurethane resin solution of

Comparative Example 3 200 parts of PTMG and 6 parts of IPDI were placed in a four-necked flask.
After charging 6.6 parts and reacting at 100 ° C. for 2 hours in a dry nitrogen atmosphere, 622 parts of DMF were homogenized in the system. At this time, NCO% was 6.3%. After the system was heated to 50 ° C., a 30% DMF solution of HMDA prepared in advance was added to 73.
5 parts (95% equivalent to the NCO group of the prepolymer) and 0.01 part of dibutyltin dilaurate as a catalyst were charged, the chain extension reaction was carried out at 70 ° C. for 5 hours, and the resin concentration was 3
A polyurethane resin solution having 0% and a viscosity of 1150 poise (20 ° C.) was obtained.

In the polyurethane resin solutions obtained in Examples 1 to 3 and Comparative Examples 1 to 3, a conventionally known weather stabilizer ("Tinuvin-P", manufactured by Ciba Geigy) was added to 100 parts of the resin solid content. A polyester film was coated with about 120 μm of the compounded liquid in which 1 part was compounded, and then dried in an oven at 80 ° C. for 3 hours to obtain a polyurethane resin film. The results of performance evaluation of this polyurethane resin film by the aforementioned evaluation method are shown in Tables 1 and 2.

[0030]

[Table 1]

[0031]

[Table 2]

[0032]

By using the method of the present invention, it becomes possible to produce a polyurethane resin having both heat yellowing resistance and light yellowing resistance and NOx gas yellowing resistance, which have been difficult by the conventional methods. The polyurethane resin composition obtained by the above method is extremely useful particularly for artificial leather and synthetic leather which are required to have light yellowing resistance, NOx gas yellowing resistance and heat resistance.

Claims (3)

[Claims] 1. A method for producing a polyurethane resin by reacting a terminal isocyanate prepolymer obtained by reacting a polymer diol with an organic diisocyanate with a chain extender, comprising: (step 1) a polymer diol (A); Step of reacting with aromatic diisocyanate (B) in an equivalent ratio of 1: 1.3 to 1: 5.0 to obtain a terminal isocyanate prepolymer; (Step 2) Isocyanate of terminal isocyanate prepolymer obtained in Step 1 A step of carrying out a first stage chain extension reaction with an aromatic diamine (extending agent I) in an amount of 40 to 80% with respect to the group; and (step 3) 90 to 110 with respect to the isocyanate group of the polymer obtained in step 2. A step of completing the chain extension reaction with a% equivalent of a low molecular weight diol (extender II); 2. A polyurethane resin composition containing the polyurethane resin obtained by the production method according to claim 1 as an essential component. 3. The polyurethane resin composition according to claim 2, which is used for artificial leather and synthetic leather.