Production of polyurethane resin

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a method for producing an ester-based urethane resin that improves hydrolysis resistance.

【0002】

[Conventional technology]

Carbodiimides are becoming more important in recent years as dehydrating agents, reaction reagents, etc., and various methods have been proposed for their synthesis.

【0003】

For example, a method of treating thiourea with cyanul chloride and alkali (Japanese Patent Publication No. 50-13248), a method of treating urea with phosphorus oxychloride and a pyridine base (Japanese Patent Laid-Open No. 60-166652), and a method of treating urea with p-toluene. Methods of treatment with sulfonyl chloride and pyridine (US Pat. No. 2,797,240) have been reported, but both of these methods require several steps to dehydrate or desulfurize thiourea or urea to obtain carbodiimides. It is not suitable for synthesizing a large amount of carbodiimide because the yield is low and a large amount of by-products can be produced.

【0004】

Further, conventionally, the use of oxides and chlorides of tungsten and vanadium as a condensation catalyst for a method for obtaining a carbodiimide by a condensation reaction involving decarbonization of isocyanate has been known (Japanese Patent Laid-Open No. 54-66656). , The activity is very low, the condensation reaction takes time, and it is not efficient.

【0005】

In addition, the metal catalysts such as sodium, lithium, and potassium described in US patents 3,345,407 and 3,502,722 are also insufficiently active and are not suitable for the synthesis of alicyclic carbodiimides having low isocyanate reactivity.

【0006】

As a highly active catalyst for the condensation reaction of isocyanate, phospholen oxides such as 3-methyl-1-phenylphosphoren-1-oxide described in JP-A-7-17990 can be mentioned. When a condensation reaction is carried out using such an organic phosphorus-based catalyst, the catalyst cannot be completely removed from the system after the condensation reaction due to its high boiling point, and only a carbodiimide composition having catalytic activity can be obtained.

【0007】

[Problems to be Solved by the Invention]

When an additive is added to urethane, it is generally better to add it at the time of synthesizing urethane because dispersion and compatibility in the system increase and the mixing step is shortened.

【0008】

When carbodiimide is added during the synthesis of urethane as a hydrolysis-resistant stabilizer of an ester-based urethane resin, carbodiimide containing a catalyst for decarbonating condensation of isocyanate cannot be used.

【0009】

Carbodiimide synthesized using an organophosphorus catalyst is not suitable because it has high activity and condenses isocyanate even with a small amount of residual catalyst.

【0010】

The present invention finds a carbodiimide that can be added during urethane synthesis, and provides a method for producing a urethane resin using the carbodiimide.

【0011】

[Means for solving problems]

As a result of diligent research to achieve the above object, the present inventors have conducted urethane as a catalyst when producing polycarbodiimide by a condensation reaction involving decarbonization of diisocyanate, as shown in the following reaction formula (1). Very low activity at the synthetic temperature of 50 ° C to 100 ° C, high activity at the synthetic temperature of polycarbodiimide in the temperature range of 150 to 200 ° C, and lost due to a small amount of water in the polyol and the hydroxyl group of the polyol. Live Ti (OR)₄(However, R may be any of an aliphatic, alicyclic, or aromatic having 10 or less carbon atoms.) Even if it is added at the time of urethane synthesis, the catalytic activity is very low, and in the presence of isocyanate. We found that we could obtain an addable polycarbodiimide, and succeeded in improving the hydrolysis resistance of urethane by adding it to urethane during synthesis.

【0012】

[Chemical 1]

<img file="JPH09255752A_D0001.tif" />【0013】

That is, the present invention improves hydrolysis resistance, which is characterized by adding polycarbodiimide at the time of synthesizing urethane resin at 50 to 100 ° C when synthesizing urethane resin from (1) diisocyanate and ester-based polyol. Method for producing ester urethane resin, (2) Diisocyanate is 0.1 to 10% by weight of Ti (OR) based on diisocyanate.₄(However, R may be any of aliphatic, alicyclic, and aromatic compounds having 10 or less carbon atoms.) De-CO for 3 to 15 hours at 150 to 200 ° C.₂(1) The production method according to (1), (3) Hexamethylene diisocyanate (HMDI), hydrogenated toluene diisocyanate (HTDI) (however, 2,4-or One or more of cyclohexamethylene diisocyanate (CHDI) (provided that it is ortho, meta, or para-substituted, or a mixture thereof). The method for producing a mixture (1) or (2).

【0014】

BEST MODE FOR CARRYING OUT THE INVENTION

More specifically, by adding a catalyst of 0.1 to 10% by weight, more preferably 0.5 to 5% by weight, to the diisocyanate and heating in a temperature range of 150 to 200 ° C under a nitrogen stream or bubbling to condense the diisocyanate. It is possible to obtain a polycarbodiimide having a very low catalytic activity.

【0015】

The polycarbodiimide of the present invention is the above Ti (OR).₄Any carbodiimide produced using a catalyst may be used, and the terminal of the polycarbodiimide may be sealed with amine, alcohol, or monoisocyanate, or the terminal isocyanate may remain as it is, and the dispersion and compatibility with the polyol may be further improved. Therefore, it is also possible to introduce a group having high compatibility with a polyol such as polyethylene glycol monomethyl ether at the terminal.

【0016】

The urethane resin of the present invention contains bifunctional diisocyanate and bifunctional diol as main components. A part of polyfunctional isocyanate or diol may be used in combination. Urethane resin diisocyanate As the diisocyanate that can be used in the present invention, any one or more kinds of diisocyanates can be used, and 1,5-naphthylene diisocyanate (may be a mixture of two or more kinds), 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyl. Dimethylmethane diisocyanate, 4,4'-dibenzyldiisocyanate, dialkyldiphenylmethane diisocyanate, 1,3-phenylenediocyanate, 1,4-phenylenediocyanate, tolylene diisocyanate, butane-1,4-diisocyanate, hexamethylene diisocyanate, isopropylene diisocyanate , Naftylene diisocyanate, methylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, cyclohexane-1,4-diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate , Lysine diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,3-bis (isocyanatemethyl) cyclohexane, methylcyclohexane diisocyanate, m-tetramethylxylylene diisocyanate, 2,4,6-triisopropylbenzene diisocyanate, isopropylidene Examples include bis (4-cyclohexamethylene diisocyanate) and trizine diisocyanate.

【0017】

Urethane resin diol The polymer polyol that can be used in the present invention is not limited as long as it is mainly a bifunctional polyester polyol. Specific examples thereof include ethylene glycol, 1,2-propanediol, 1,3-propanediol, and 1,3-. Saturated and unsaturated low molecular weight glycols such as butanediol, 1,4-butanediol, neopentyl glycol, pentandiol, hexanediol, octanediol, 1,4-butinediol, diethylene glycol, triethylene glycol, and dipropylene glycol. In addition, alkyl glycidyl ethers such as n-butyl glycidyl ether and 2-ethylhexyl glycidyl ether, monocarboxylic acid glycidyl esters such as persatic acid glycidyl ester, and adipic acid, phthalic acid, isophthalic acid, terephthalic acid, maleic acid, and fumaric acid. Dibasic acids such as oxalic acid, oxalic acid, malonic acid, glutaric acid, pimelli acid, speric acid, azelaic acid, sebacic acid, dimer acid, or polyester polyols obtained by dehydration condensation of these anhydrides, and cyclics. Examples thereof include various known high molecular weight polyols such as polyester polyols obtained by open polymerization of an ester compound.

【0018】

In the urethane resin of the present invention, INDEX = NCO / OH is preferably in the range of 0.8 to 1.5, more preferably 1.0 to 1.1, and outside this range, preferable urethane cannot be obtained and the urethane does not cure.

【0019】

The carbodiimide of the present invention is Cardinal number (degree of polymerization n) The number of carbodiimide groups is preferably 1 to 30, particularly preferably 3 to 15. If it is 30 or more, the melting point and viscosity are high and it is difficult to disperse and mix well with urethane raw materials. If it is 3 or less, hydrolysis stabilization performance cannot be obtained.

【0020】

The carbodiimide may be sealed with an NCO (isocyanate) terminal (in this case, the carbodiimide is introduced into the urethane molecular chain) or one having one group that reacts with a suitable NCO. Absent. Examples thereof include monofunctional alcohols, amines, monoisocyanates, etc. Examples of alcohols include methanol, ethanol, propanol, butanol, pentanol, isopropanol, hexanol, cyclohexanol, 2-ethylhexanol, heptanol, octanol, nonanol, decanol. , Phenol, polyethylene glycol monomethyl or ethyl ether, cresol, polypropylene glycol monomethyl or ethyl ether, polymethylene glycol monomethyl or ethyl acetate, polypropylene glycol monomethyl or ethyl acetate, etc. As amines, butylamine, isopropylamine, cyclohexylamine, aniline, dibutylamine , Diisopropylamine and the like, examples of the monoisocyanate include butyl isocyanate, cyclohexyl isocyanate and the like.

【0021】

Amount of carbodiimide The NCN group content is preferably 1 × 10 per 1 g of urethane.^-2~10^-6Mol, more preferably 1x10^-3~10^-5It is in the range of moles. If this range is exceeded, a highly elastic and desirable urethane cannot be obtained. Further, if it falls below this range, hydrolysis performance cannot be obtained.

【0022】

As the carbodiimide of the present invention, the following carbodiimides derived from diisocyanate can be used. HMDI: 4,4'-dicyclohexylmethane diisocyanate HTDI: 2,4- and / or 2,6-hydrogenated tolylene diisocyanate CHDI: Ortho, Meta, Rose (either or mixed), Cyclohexyl diisocyanate [0023]

The urethane resin synthesis method of the present invention can be synthesized by a known method.

【0024】

(1) The following materials are used as raw materials. PO: Polyol M: Diisocyanate such as MDI CI: Carbodiimide PPO: OH-terminated prepolymer PPN: NCO-terminated prepolymer CE: Chain extenders, such as the diols and diamines listed above (ethylenediamine, propylenediamine, triethylenediamine, butatirenideamine, hexylenediamine) [0025]

(2) Urethane synthesis example The following urethanization reaction is carried out in the range of 20 ° C to 200 ° C. Preferably 60 ° C to 150 ° C. Since the urethanization reaction is an exothermic reaction, strict temperature control cannot be performed. If it is too low, the reaction will be slow and time consuming. If it is too high, the reaction will be too fast, causing poor mixing, and the reaction will not be uniform. In addition, urethane deteriorates (burns).

【0026】

When the reaction is slow, a general urethanization catalyst such as amines (triethylenediamine, etc.) and organic tins (dibutyltin dilaurate, etc.) can be used in the range of 0.001 to 1 wt% with respect to urethane.

【0027】

One or more kinds of solvents such as DMF (dimethylformamide), THF (tetrahydroxyfuran), MEK (methylethylketone), toluene, and DMAC (dimethylacetamide) may be used in the synthesis.

【0028】

Urethane can be obtained by adding a mixture of M and Cl to PO and reacting at 80 ° C for about 1 to 3 hours to synthesize PPN and adding CE to it. M is added to PO and reacted at 120 ° C for 1 to 3 hours to synthesize PPO, and Cl is added to it to extend the chain to obtain urethane. For example, PO and M are reacted at 120 ° C for 1 to 3 hours to synthesize PPO, Cl is added, and further reacted at 130 ° C for 1 to 3 hours to synthesize PPN, and CE is added to synthesize urethane. To do. Cl is added to PO and reacted at 130 ° C for 1 to 3 hours to synthesize PPO, then M is added and reacted at 120 ° C for 1 to 3 hours to synthesize urethane. Cl is added to PO and reacted at 130 ° C for 1 to 3 hours to synthesize PPO, then M is added and reacted at 120 ° C for 1 to 3 hours to synthesize PPN, and CE is added to synthesize urethane. To do. Urethane is obtained by reacting PO and Cl and PO and M at a predetermined temperature to synthesize PPN and PPO, and mixing them. PPN and PPO are synthesized by reacting PO and Cl and PO and M at a predetermined temperature, PPN is synthesized by mixing them, and urethane is obtained by adding CE.

【0029】

When no solvent is used, the obtained urethane becomes a solid at room temperature, and it is dissolved in the solvent and used as a solution, crushed and used as a powder, or further in the range of 150 ° C to 250 ° C. Preferably, an extruder or injection molding machine is used in the range of 170 ° C to 200 ° C to form or spin the product. Of course, the urethane may be introduced into an apparatus such as an extruder before the urethane solidifies, and the urethanization reaction may be completed while melting and kneading there.

【0030】

Various isocyanate blocking agents such as oximes (methyl ethyl ketooxime, cyclohexyl keto oxime, etc.), phenols such as phenol and xylylene, alcohols such as methanol, ethanol, cyclohexanol, amines, amides, imides, ε-caprolactam, etc. Dicarbonyl compounds such as lactams, diethylmalonate, and ethylacetacetate are used to block the isocyanate, and when used, the isocyanate is dissociated by heating and reacted with a chain spreading agent and a polyol to form urethane to obtain urethane. It is also possible. Similarly, it is also possible to block the chain extender and use, for example, blocked amines to regenerate the amines with water due to humidity during use to form (cure) urethane.

【0031】

Further, various additives such as a light stabilizer and an antioxidant may be used in combination.

【0032】

[Example]

&lt;Catalyst used in synthesis example&gt; [0033]

[table 1]

<img file="JPH09255752A_D0002.tif" />【0034】

&lt;Synthesis Example 1&gt; 2 g of catalyst A was added to 200 g of HMDI and heated at 180 ° C for 2 hours while stirring at 200 rpm using a mechanical stirrer to obtain polycarbodiimide with n (degree of polymerization) = 5.1.

【0035】

The table below summarizes the composites in the same manner.

【0036】

&lt;Synthesis Examples 2 to 10&gt; Carbodiimides shown in Table 2 were obtained by synthesizing in the same manner as in Synthesis Example 1 except that the types of catalysts were changed to B to J.

【0037】

[Table 2]

<img file="JPH09255752A_D0003.tif" />【0038】

&lt;Synthesis Examples 11 to 15&gt; Carbodiimides as shown in Table 3 were obtained by changing the raw materials and reaction conditions.

【0039】

[Table 3]

<img file="JPH09255752A_D0004.tif" />【0040】

&lt;Synthesis Examples 16 to 20&gt; Carbodiimides as shown in Table 4 were obtained by changing the raw materials and reaction conditions.

【0041】

[Table 4]

<img file="JPH09255752A_D0005.tif" />【0042】

&lt;Synthesis Examples 21 to 30&gt; Carbodiimides with sealed ends as shown in Table 5 were obtained by changing the raw materials and reaction conditions.

【0043】

[Table 5]

<img file="JPH09255752A_D0006.tif" />【0044】

&lt;Synthesis Example 31&gt; HMDI 1572 g and polyethylene glycol monomethyl ether-ethylene group number 3 (PEG3) 328 g are heated and reacted at 130 ° C for 3 hours while stirring at 200 rpm using a mechanical stirrer, and catalyst A is further added thereto. 47 g was added and a carbodiimide reaction was carried out at 180 ° C. for 37 hours to obtain a terminally sealed polycarbodiimide having n (degree of polymerization) = 5.0.

【0045】

&lt;Synthesis Examples 32 to 40&gt; Carbodiimides as shown in Table 6 were obtained by changing the type of catalyst and reaction time.

【0046】

[Table 6]

<img file="JPH09255752A_D0007.tif" />【0047】

&lt;Synthesis Example 41&gt; 31 g of catalyst A was added to 1048 g of HMDI, and the mixture was reacted at 180 ° C for 42 hours while stirring at 200 rpm using a mechanical stirrer to obtain an isocyanate-terminated carbodiimide with n = 3. It was allowed to cool to 130 ° C., 768 g of polyethylene glycol monomethyl ether (ethylene group number n = 8) was added, and the mixture was reacted at 130 ° C. for 3 hours while continuing stirring to obtain a terminally sealed carbodiimide.

【0048】

&lt;Synthesis Examples 42 to 50&gt; Carbodiimides as shown in Table 7 were obtained by changing the type of catalyst and reaction time.

【0049】

[Table 7]

<img file="JPH09255752A_D0008.tif" />【0050】

&lt;Comparative example&gt; Add 2 g of 3-methyl-1-phenyl-2-phosphorene-1-oxide as a catalyst to 200 g of HMDI and heat at 180 ° C for 7 hours while stirring at 200 rpm using a mechanical stirrer to n = 4.9. Polycarbodiimide was obtained.

【0051】

&lt;Urethane synthesis example&gt; 1.994 kg of MDI, 11.162 kg of molecular weight 2113 adipic acid-based polyester polyol and 200 g of carbodiimide were mixed and reacted at 80 ° C for 3 hours with a mechanical stirrer, and 1.221 kg of MDI was added to 80 °. The reaction was carried out in C for 1 hour to obtain an isocyanate-terminated prepolymer. Butanediol 0.624 kg was added to this prepolymer to obtain a urethane resin.

【0052】

The urethane to which carbodiimide was added obtained in the above &lt;Synthesis Example 1&gt; and the synthesis examples of Synthesis Nos. 2 to 50 shown in the table was obtained satisfactorily. (Urethane No.1 ~ 50) [0053]

&lt;Hydrolyzed test&gt; The obtained urethane was melt-extruded by a uniaxial extruder and formed into a film using a T-die. The obtained film was punched into dumbbell No. 4 and used as a test piece (about 200 μm thick). The obtained test piece was immersed in water at 95 ° C., and the tensile strength after 0 days and 10 days was measured and shown in Tables 8 and 9.

【0054】

Tables 10 and 11 show the tensile elongation at break (JIS-K6301) after 0 days and 10 days after immersion in water at 95 ° C.

【0055】

[Table 8]

<img file="JPH09255752A_D0009.tif" />【0056】

[Table 9]

<img file="JPH09255752A_D0010.tif" />【0057】

[Table 10]

<img file="JPH09255752A_D0011.tif" />【0058】

[Table 11]

<img file="JPH09255752A_D0012.tif" />【0059】

[Effect of the invention]

The urethane resin synthesized by adding the carbodiimide of the comparative example showed rapid thickening accompanied by foaming at the time of synthesizing the prepolymer. Further, the tensile strength and the elongation are extremely lowered because the molecular weight of urethane does not increase due to poor stirring for thickening, and bubbles due to foaming are mixed in the urethane.

【0060】

The urethane resin of the present invention showed good hydrolysis resistance.