JP2012062370A - Biodegradable polyurethane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide biodegradable polyurethane having high strength, excellent in toughness and moldability, and not generating harmful amine after decomposition.SOLUTION: This biodegradable polyurethane is obtained by reacting a biodegradable polyol, diisocyanate and a chain extender, wherein the biodegradable polyol is poly-ε-caprolactone diol, and the diisocyanate is lysine diisocyanate or 1-3C alkyl ester thereof or butane diisocyanate, and the chain extender is 1, 4-butanediol.

Description

  The present invention relates to a biodegradable polyurethane having high strength, excellent toughness and moldability, and does not generate harmful amines after decomposition.

Since environmental pollution caused by plastic waste has become a global problem, many biodegradable plastics that can be decomposed in the natural environment have been developed. Various attempts have also been made to impart biodegradability to polyurethane obtained by reacting polyol and diisocyanate. However, biodegradable polyurethanes are often inferior in physical properties, mechanical properties, or chemical properties compared to conventional polyurethanes that are not biodegradable, and can be used as a substitute for conventional polyurethanes. There is a need for a flexible polyurethane.
From such a viewpoint, high-strength biodegradable polyurethane has been developed. Specifically, poly-ε-caprolactone diol as a polyol, lysine diisocyanate (LDI) or its C 1-3 alkyl ester or butane diisocyanate (BDI) as a diisocyanate, and a prepolymer having an isocyanate group at the terminal A high strength biodegradable polyurethane and a biodegradable polyurethane produced and further obtained using 1,4-butanediamine (1,4-BDA) or 1,3-propanediol (1,3-PDO) as chain extenders Degradable polyurethaneurea has been developed (see Non-Patent Documents 1 and 2). In addition, biodegradable polyurethaneurea obtained by using 1,2-propanediamine as a chain extender has been developed from the viewpoint of improving toughness with respect to the materials disclosed in Non-Patent Documents 1 and 2. (See Patent Document 1).

JP 2009-203404 A

Shirahase, Takahara et al., Japan Rubber Association 82, 349 (2009) Hatano, Takahara et al., Japan Rubber Association 79, 219 (2006)

The biodegradable polyurethane urea disclosed in Patent Document 1 is flexible but has a problem of low strength.
Further, the inventors further examined the biodegradable polyurethane and biodegradable polyurethane urea disclosed in Non-Patent Documents 1 and 2, and as a result, poly-ε-caprolactone diol (PCL) as a polyol and lysine diisocyanate as a diisocyanate. When (LDI) is used and 1,4-butanediamine (1,4-BDA) is used as a chain extender, the obtained biodegradable polyurethaneurea has high strength, but is soluble in various solvents. It was found that the moldability was poor. Further, when the diisocyanate was changed to butane diisocyanate (BDI) without changing the polyol and the chain extender, the strength of the resulting biodegradable polyurethaneurea was very high, but the moldability was further deteriorated. Furthermore, when the chain extender was changed to 1,3-propanediol (1,3-PDO) without changing the polyol and diisocyanate, the moldability was improved, but the strength was reduced.
In addition, some biodegradable polyurethaneureas have a problem that, depending on the type of diisocyanate used, harmful amines are generated after decomposition.
Thus, a biodegradable polyurethane that has high strength, toughness, and moldability and does not generate harmful amines after decomposition has not been developed yet.
Accordingly, an object of the present invention is to provide a biodegradable polyurethane that has high strength, is excellent in toughness and moldability, and does not generate harmful amines after decomposition.

  As a result of intensive studies to solve the above problems, the present inventors have found that poly-ε-caprolactone diol (PCL) as a biodegradable polyol, lysine diisocyanate (LDI) as a diisocyanate, or an alkyl ester having 1 to 3 carbon atoms thereof, or By using butane diisocyanate (BDI) and 1,4-butanediol (1,4-BDO) as a chain extender, high strength, excellent toughness and moldability, and generation of harmful amines after decomposition It has been found that a biodegradable polyurethane can be provided.

That is, the present invention relates to the following [1] to [4].
[1] A biodegradable polyurethane obtained by reacting a biodegradable polyol, diisocyanate and a chain extender,
The biodegradable polyol is poly-ε-caprolactone diol, the diisocyanate is lysine diisocyanate, an alkyl ester having 1 to 3 carbon atoms, or butane diisocyanate, and the chain extender is 1,4-butanediol. A biodegradable polyurethane characterized by
[2] The biodegradation according to [1], which is obtained by reacting the biodegradable polyol and the diisocyanate to obtain a prepolymer, and then reacting the obtained prepolymer with the chain extender. Polyurethane.
[3] The use ratio of the biodegradable polyol and the chain extender (biodegradable polyol: chain extender) is 1: 3 to 3: 1 in molar ratio, and the biodegradable polyol and the chain extender [1] or [1] above, wherein the total number of moles of the chain extender and the use ratio of the diisocyanate (“biodegradable polyol + chain extender”: diisocyanate) is from 2: 3 to 3: 2 in molar ratio. The biodegradable polyurethane as described in [2].
[4] The biodegradable polyurethane according to any one of [1] to [3], wherein the diisocyanate is butane diisocyanate.

  According to the present invention, it is possible to provide a biodegradable polyurethane that has high strength, is excellent in toughness and moldability, and does not generate harmful amines after decomposition.

[Biodegradable polyurethane]
The biodegradable polyurethane of the present invention is a biodegradable polyurethane obtained by reacting a biodegradable polyol, a diisocyanate and a chain extender, wherein the biodegradable polyol is poly-ε-caprolactone diol, Is lysine diisocyanate or an alkyl ester having 1 to 3 carbon atoms or butane diisocyanate, and the chain extender is 1,4-butanediol.
Hereinafter, the components used for producing the biodegradable polyurethane of the present invention will be described in detail.

(Biodegradable polyol)
In the present invention, at least poly-ε-caprolactone diol (PCL) is used as the biodegradable polyol. If it is this PCL, not only will it have biodegradability, but a polyurethane with high strength and excellent toughness and moldability can be obtained by the combination with other specific components described above.
The molecular weight of PCL is preferably 500 to 3,000, more preferably 800 to 2,000, and still more preferably 1,000 to 1,500. When the molecular weight of PCL is 500 or more, the resulting polyurethane has good elongation, and when it is 3,000 or less, a high-strength polyurethane is obtained and the polyurethane is difficult to crystallize.
As the biodegradable polyol, a polyol other than PCL may be used in combination as long as the effects of the present invention are not significantly reduced. Examples of polyols other than PCL include known polyols used in the production of polyurethanes. Specific examples thereof include polyhydroxycarboxylic acids such as polyglycolic acid, polylactic acid, polyhydroxybutyric acid, and polyhydroxyvaleric acid; poly Polyester polyols obtained by condensation reaction of dibasic acid and diol, such as butylene succinate and polybutylene adipate; polyoxyethylene glycol, polyoxypropylene glycol, poly (oxyethylene) (oxypropylene) glycol, polyoxybutylene glycol And polyether polyols such as polyoxytetramethylene glycol. These known polyols may be used alone or in combination of two or more.
The amount of the PCL used relative to the total amount of the biodegradable polyol used is preferably 40% by mass or more, more preferably 50% by mass or more, more preferably 80% by mass or more, from the viewpoint of sufficiently expressing the effects of the present invention. More preferably, it is 90 mass% or more, More preferably, it is 95 mass% or more, Most preferably, it is substantially 100 mass%.

(Diisocyanate)
In the present invention, at least lysine diisocyanate (LDI) or an alkyl ester having 1 to 3 carbon atoms thereof (hereinafter sometimes collectively referred to as lysine diisocyanates (LDIs)) or butane diisocyanate (BDI) is used as the diisocyanate. The LDIs and BDI may be used alone or in combination of two or more. Examples of the alkyl ester having 1 to 3 carbon atoms of LDI include lysine diisocyanate methyl ester and lysine diisocyanate ethyl ester, and lysine diisocyanate methyl ester is preferable.
When the biodegradable polyurethane of the present invention is decomposed, the diisocyanate becomes an amine body, but the lysine diisocyanates and the amine body of butane diisocyanate are biogenic amines or essential amino acids, and thus have no adverse effects on the human body. Moreover, if it is a combination of lysine diisocyanates or butane diisocyanate and the above-mentioned other specific components, a polyurethane having high strength and excellent toughness and moldability can be obtained. The diisocyanate is preferably BDI from the viewpoint of strength and toughness.
As the diisocyanate, diisocyanates other than LDIs and BDI may be used in combination as long as the effects of the present invention are not significantly reduced. Examples of diisocyanates other than LDIs and BDI include known diisocyanates used in the production of polyurethane.
Examples of the known diisocyanate include aromatic diisocyanates and aliphatic diisocyanates. Specific examples of the aromatic diisocyanate include 4,4′-diphenylmethane diisocyanate, tolylene diisocyanate, tolidine diisocyanate, xylylene diisocyanate, naphthalene diisocyanate, paraphenylene diisocyanate, tetramethylxylene diisocyanate, and the like. Specific examples of the aliphatic diisocyanate include hexamethylene diisocyanate, isophorone diisocyanate, norbornene diisocyanate, dimer acid diisocyanate, trimethylhexamethylene diisocyanate, dicyclohexylmethane diisocyanate, and hydrogenated xylylene diisocyanate. These known diisocyanates may be used alone or in combination of two or more.
The amount of LDI or BDI used relative to the total amount of diisocyanate used is preferably 40% by mass or more, more preferably 50% by mass or more, more preferably 80% by mass or more, from the viewpoint of sufficiently expressing the effects of the present invention. More preferably, it is 90 mass% or more, More preferably, it is 95 mass% or more, Most preferably, it is substantially 100 mass%.

(Chain extender)
In the present invention, at least 1,4-butanediol is used as the chain extender. It is important that the diol has 4 straight carbon atoms and no branched chain, such as 1,4-butanediol. In the present invention, by using 1,4-butanediol as a chain extender together with the specific biodegradable polyol and the specific diisocyanate, the resulting biodegradable polyurethane is stronger than the conventional biodegradable polyurethane. The toughness and moldability are superior to conventional biodegradable polyurethane.
As the chain extender, a chain extender other than 1,4-butanediol may be used in combination as long as the effect of the present invention is not significantly reduced. Examples of the chain extender other than 1,4-butanediol include known chain extenders used for producing polyurethane. Known chain extenders include polyhydric alcohols having a molecular weight of preferably 350 or less, more preferably 200 or less. Specific examples of the polyhydric alcohol include, for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, 1,3-butanediol, and 3-methyl-1,5-pentane. Examples include diol, 1,6-hexanediol, 1,9-nonanediol, 1,4-cyclohexanedimethanol and the like.
The amount of 1,4-butanediol used relative to the total amount of the chain extender used is preferably 80% by mass or more, more preferably 90% by mass or more, and more preferably 95% by mass, from the viewpoint of sufficiently expressing the effects of the present invention. % Or more, more preferably substantially 100% by mass.

  The biodegradable polyurethane of the present invention may further contain a plasticizer. Examples of the plasticizer include glycerin ester, fatty acid ester, maleic acid ester, and fumaric acid ester.

(Use ratio of each component)
The use ratio of the biodegradable polyol and the chain extender (biodegradable polyol: chain extender) is preferably 1: 3 to 3: 1 in molar ratio, and the biodegradable polyol and the chain The use ratio of the total of the extender and the diisocyanate (“biodegradable polyol + chain extender”: diisocyanate) is preferably 2: 3 to 3: 2 in molar ratio. More preferably, biodegradable polyol: chain extender = 1: 2 to 2: 1 (molar ratio) and “biodegradable polyol + chain extender”: diisocyanate = 2: 3 to 3: 2 (molar ratio) It is. More preferably, biodegradable polyol: chain extender = 4: 5 to 5: 4 (molar ratio) and “biodegradable polyol + chain extender”: diisocyanate = 4: 5 to 5: 4 (molar ratio) It is. Particularly preferably, the total amount of biodegradable polyol and chain extender used is substantially the same as the molar ratio of the diisocyanate.
When the use ratio of each component is in the above range, the obtained biodegradable polyurethane has higher strength than the conventional biodegradable polyurethane, and has better toughness and moldability than the conventional biodegradable polyurethane. Become.

In addition, it is good also as a biodegradable polyurethane foam by making the said each component react using a foaming agent, a foam stabilizer, a catalyst, etc. as needed.
As a foaming agent, the well-known foaming agent used for manufacture of a polyurethane foam can be used, For example, water, a methylene chloride, etc. are mentioned.
As the catalyst, an amine-based catalyst is preferable. The amine-based catalyst includes a foamed amine catalyst and other catalysts, and these are usually used in combination. The foaming amine catalyst has an activity ratio of foaming activity to resinization activity (foaming activity / resinization activity) of 30 × 10 ⁻¹ or more, for example, N, N, N ′, N ″, N ″ -pentamethyldiethylenetriamine, bis (2-dimethylaminoethyl) ether, N ′, N ′, N ″, N ″ -pentamethyldipropylenetriamine, N, N-dimethylaminoethoxyethanol, N, N , N′-trimethylaminoethoxyethanol, N, N, N ′, N ″, N ′ ″, N ′ ″-hexamethyltriethylenetetramine, N, N, N ′, N ″ -tetramethyl- N ″-(2-hydroxylethyl) triethylenediamine, N, N, N ′, N ″ -tetramethyl- (2-hydroxylpropyl) triethylenediamine and the like can be mentioned. Among these, N, N, N ′, N ″, N ″ -pentamethyldiethylenetriamine and bis (2-dimethylaminoethyl) ether are preferable, and bis (2-dimethylaminoethyl) ether is more preferable. The amine-based catalyst other than the foamed amine catalyst is an amine-based catalyst having an activity ratio of less than 30 × 10 ⁻¹ , and examples thereof include triethylenediamine, N-ethylmorpholine, dimethylethylethanolamine and the like.
As the catalyst, in addition to the amine catalyst, a catalyst that is not an amine catalyst, for example, an organometallic catalyst may be used in combination. As the organometallic catalyst, a metal salt of a carboxylic acid can be used, and examples of the metal salt include a tin salt and a bismuth salt. More specifically, as the organometallic catalyst, tin octylate (stannas octoate), bismuth octylate (bismuth octoate), tin oleate (stannas oleate), dibutyltin diacetate, dibutyltin dilaurate, dibutyltinthio Examples include carboxylate, dibutyltin dimaleate, and dioctyltin thiocarboxylate.

As a foam stabilizer, the well-known foam stabilizer used for manufacture of a polyurethane foam can be used. Among these, silicone made of a polydimethylsiloxane-polyoxyalkylene copolymer is preferable because the cell diameter is stabilized when foamed and cured by the combined use of introduction of inert gas and mechanical stirring. The molecular structure of the polydimethylsiloxane-polyoxyalkylene copolymer is usually composed of a polydimethylsiloxane part having a molecular weight of about 350 to 15,000 and a polyoxyalkylene part having a molecular weight of about 200 to 9,000. The molecular structure is preferably an addition polymer of ethylene oxide or a co-addition polymer of ethylene oxide and propylene oxide, and its terminal is preferably ethylene oxide.
Further, a reactive silicone having a functional group having reactivity with an isocyanate group is preferable. Examples of the functional group include a hydroxyl group, an amino group, a mercapto group, a carboxyl group, and an epoxy group.

(Method for producing biodegradable polyurethane)
There is no restriction | limiting in particular in the manufacturing method of the biodegradable polyurethane of this invention, The manufacturing method of a well-known polyurethane is employable. For example, it may be produced by reacting the biodegradable polyol, the diisocyanate and the chain extender by a one-shot method, or after reacting the biodegradable polyol and the diisocyanate to obtain a prepolymer, You may manufacture by the so-called prepolymer method which makes the obtained prepolymer and the said chain extender react.
In any method, the reaction temperature is usually preferably 50 to 120 ° C, more preferably 70 to 110 ° C. In addition, the prepolymer method is preferably carried out by dropping a chain extender into the prepolymer. The dropping time (reaction time) of the chain extender is not particularly limited, but is usually preferably about 10 minutes to 20 hours, more preferably 20 minutes to 15 hours. The chain extender may be dropped after being dissolved in an aprotic organic solvent described later.
The reaction between the prepolymer and the chain extender is preferably carried out in the presence of an alkali metal halide salt or an alkaline earth metal halide salt. Examples of the alkali metal halide include sodium chloride, potassium chloride, lithium chloride, sodium bromide, potassium bromide, and lithium bromide. Examples of the alkaline earth metal halide salt include calcium chloride, magnesium chloride, barium chloride, calcium bromide, magnesium bromide, barium bromide and the like.
The production of the biodegradable polyurethane may be carried out in the presence of an aprotic organic solvent. As the aprotic organic solvent, a known organic solvent used in the production of polyurethane can be used. For example, esters such as ethyl acetate; nitriles such as acetonitrile; ethers such as tetrahydrofuran; N, N-dimethylformamide, N Amides such as N, dimethylacetamide, and the like, but are not particularly limited thereto.
In addition, as above-mentioned, you may form a biodegradable polyurethane foam by performing the said reaction in presence of a foaming agent, a foam stabilizer, a catalyst, etc. as needed.

(Properties of biodegradable polyurethane)
The biodegradable polyurethane of the present invention has a breaking elongation measured by the method described in the Examples of 950 to 1800%, specifically 1000 to 1700%. Moreover, the breaking strength measured by the method as described in an Example is 13-25 Mpa, specifically 14-23 Mpa.
Furthermore, the biodegradable polyurethane of the present invention comprises amides such as N, N-dimethylformamide (DMF); sulfoxides such as dimethyl sulfoxide (DMSO); ethers such as tetrahydrofuran (THF); 1,1,1,3,3 , 3-hexafluoro-2-propanol (HFIP), alcohols such as methanol, ethanol, isopropanol; soluble in organic solvents such as halogenated hydrocarbons such as chloroform;

EXAMPLES Next, although an Example demonstrates this invention still in detail, this invention is not limited at all by these examples.
In addition, about the biodegradable polyurethane obtained by the Example and the comparative example, the breaking elongation rate and breaking strength were measured in accordance with the following method. Further, the solubility in an organic solvent was investigated and used as an index of moldability.

(Elongation at break-toughness-)
Using a film molded by the solvent casting method, the tensile speed was measured at 10 mm / min according to “JIS K6251 vulcanized rubber and thermoplastic rubber—How to obtain tensile properties”.
The elongation at break was evaluated according to the following evaluation criteria and used as an index of toughness.
◎: 1000% or more ○: 600% or more to less than 1000% ×: less than 600%

(Breaking strength)
The breaking strength was measured by the same operation as the breaking elongation rate.
The breaking strength was evaluated according to the following evaluation criteria.
◎: 13 MPa or more ○: 5 MPa or more, less than 13 MPa ×: less than 5 MPa

(Solubility in organic solvents-Moldability-)
The solubility of the biodegradable polyurethane obtained in each example in the following organic solvent was investigated. When it was judged that 0.05 part by mass was completely dissolved with respect to 1 part by mass of the organic solvent, it was judged as “soluble”.
(I) N, N-dimethylformamide (DMF)
(Ii) Dimethyl sulfoxide (DMSO)
(Iii) Tetrahydrofuran (THF)
(Iv) 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP)
(V) Methanol, ethanol, isopropanol (vi) Chloroform In addition, it evaluated according to the following evaluation criteria and used it as the index of moldability.
A: Soluble in all of the organic solvents (i) to (vi). X: Three or less of the organic solvents (i) to (vi) are soluble.

<Example 1>
A flask was charged with 25 g (10 mmol) of poly-ε-caprolactone diol, which is a biodegradable polyol, and dissolved at 50 to 60 ° C. Thereto, 8.48 g (40 mmol) of lysine diisocyanate methyl ester was added and reacted at 80 ° C. for 3 hours to obtain a prepolymer.
Next, 80 mL of N, N-dimethylformamide and a tin catalyst were added to the flask, and 1.76 g (20 mmol) of 1,4-butanediol mixed with 80 g of N, N-dimethylformamide was dropped into the flask at room temperature. For 12 hours.
The obtained polymer was purified by reprecipitation with water to obtain a biodegradable polyurethane. The biodegradable polyurethane obtained was measured for elongation at break and strength at break, and the solubility in an organic solvent was investigated as an index of moldability. The results are shown in Table 1.

<Example 2, Comparative Examples 1-11>
A biodegradable polyurethane was produced in the same manner as in Example 1, except that the components, amounts used, and reaction time with the prepolymer were changed as shown in Table 1. The biodegradable polyurethane obtained was measured for elongation at break and strength at break, and the solubility in an organic solvent was investigated as an index of moldability. The results are shown in Table 1.

From Table 1, it can be seen that the biodegradable polyurethane of the present invention has high strength and is excellent in toughness and moldability. The biodegradable polyurethane of the present invention does not generate harmful amines after decomposition.
On the other hand, the biodegradable polyurethanes obtained in Comparative Examples 1 to 5 were obtained by using PCL as the biodegradable polyol, LDI as the diisocyanate, and 1,4-butanediamine as the chain extender. In addition, it has poor toughness, and some of them have lower strength.
The biodegradable polyurethanes obtained in Comparative Examples 6 to 8 were obtained using PCL as the biodegradable polyol, LDI as the diisocyanate, and 1,3-propanediol as the chain extender, and the moldability was good. However, in addition to poor toughness, some have low strength.
The biodegradable polyurethanes obtained in Comparative Examples 9 to 11 were obtained using PCL as the biodegradable polyol, BDI as the diisocyanate, and 1,4-butanediamine as the chain extender, and had a strength. High and good toughness but poor moldability.

  The biodegradable polyurethane of the present invention can be used for conventional polyurethane applications. For example, in addition to general uses as polymer films and sheets, tubes, foams, fibers, food trays, chopsticks, spoons, forks, cups, garbage bags, heat insulation cases, wrap films, sponges, bottles, water absorption sheets, moisture retention sheets , Agricultural mulching film, base material for disc case, polymer staple, blister pack, laminate, microcapsule for medicine, microcapsule for fertilizer and soil conditioner, suture thread, syringe, disposable clothing, support for treatment such as fractures or Osteosynthesis, grafting device or graft, fishing line, fishnet, simulated bait, golf ball, adhesive, hot melt adhesive, packing band, adhesive tape, cushioning material, eyeglass frame, short fiber, long fiber, non-woven fabric, It can be used for porous substrates.

Claims (4)

A biodegradable polyurethane obtained by reacting a biodegradable polyol, diisocyanate and a chain extender,
A biodegradable polyurethane, wherein the biodegradable polyol is poly-ε-caprolactone diol, the diisocyanate is lysine diisocyanate or butane diisocyanate, and the chain extender is 1,4-butanediol.   The biodegradable polyurethane according to claim 1, which is obtained by reacting the biodegradable polyol and the diisocyanate to obtain a prepolymer, and then reacting the obtained prepolymer with the chain extender.   The use ratio of the biodegradable polyol and the chain extender (biodegradable polyol: chain extender) is 1: 3 to 3: 1 in molar ratio, and the biodegradable polyol and the chain extender The total number of moles and the use ratio of the diisocyanate ("biodegradable polyol + chain extender": diisocyanate) is 2: 3 to 3: 2 in molar ratio. Biodegradable polyurethane.   The biodegradable polyurethane according to any one of claims 1 to 3, wherein the diisocyanate is butane diisocyanate.