JP2022191686A - Casting polyurethane elastomer - Google Patents

Abstract

To provide a polyurethane elastomer having both of excellent mechanical properties and excellent pot life.SOLUTION: In a polyurethane elastomer including a reaction product of an isocyanate group-terminated prepolymer and a curing agent, the isocyanate group-terminated prepolymer includes a reaction product of a polyisocyanate component including an aromatic polyisocyanate and a polyol component including a crystalline macropolyol; the curing agent includes a linear polyhydric alcohol containing sulfur and/or oxygen other than a hydroxyl group; and the content ratio of the linear polyhydric alcohol containing sulfur and/or oxygen other than a hydroxyl group to the total amount of the curing agent is 20 mass% or more.SELECTED DRAWING: None

Description

The present invention relates to polyurethane elastomers.

Polyurethane elastomers have hard segments formed by reaction of polyisocyanate and low-molecular-weight polyol, and soft segments formed by reaction of polyisocyanate and macropolyol. Polyurethane elastomers are rubber elastomers and have excellent mechanical properties, and are therefore widely used in various industrial fields.

More specifically, polyurethane elastomers obtained by the following methods are known. Specifically, in this method, first, a polyalkylene oxide having a molecular weight of 2000 is reacted with 4,4'-diphenylmethane diisocyanate to synthesize an NCO group-terminated urethane prepolymer. Next, the NCO group-terminated urethane prepolymer and 1,4-butanediol are mixed to obtain a polyurethane elastomer-forming composition. The polyurethane elastomer-forming composition is then poured into a mold and allowed to cure. Thereby, a polyurethane elastomer is obtained (see, for example, Patent Document 1 (Example 1)).

JP 2017-190394 A

On the other hand, polyurethane elastomer-forming compositions are required to have an excellent pot life from the viewpoint of workability. However, the polyurethane elastomer-forming composition of Patent Document 1 does not have a sufficient pot life.

The present invention is a polyurethane elastomer having both excellent mechanical properties and an excellent pot life.

The present invention [1] is a polyurethane elastomer comprising a reaction product of an isocyanate group-terminated prepolymer and a curing agent, wherein the isocyanate group-terminated prepolymer comprises a polyisocyanate component containing an aromatic polyisocyanate, a crystalline macromolecule a reaction product with a polyol component comprising a polyol, wherein the curing agent comprises a linear polyhydric alcohol containing oxygen and/or sulfur other than hydroxyl groups; It contains a polyurethane elastomer in which the content of the linear polyhydric alcohol containing oxygen and/or sulfur is 20% by mass or more.

The present invention [2] includes the polyurethane elastomer according to [1] above, wherein the aromatic polyisocyanate contains diphenylmethane diisocyanate.

In the present invention [3], the content of the linear polyhydric alcohol containing oxygen other than hydroxyl groups is 20 with respect to the total amount of the linear polyhydric alcohols containing oxygen and/or sulfur other than hydroxyl groups. It contains the polyurethane elastomer according to the above [1] or [2], which is at least 10% by mass.

The present invention [4] provides the polyurethane elastomer according to any one of the above [1] to [3], wherein the linear polyhydric alcohol containing oxygen and/or sulfur other than hydroxyl groups contains diethylene glycol. , including

The present invention [5] is the above [1], wherein the content of the linear polyhydric alcohol containing oxygen and/or sulfur other than hydroxyl groups is 80% by mass or more with respect to the total amount of the curing agent. The polyurethane elastomer according to any one of [4] is included.

In the polyurethane elastomer of the present invention, the isocyanate group-terminated prepolymer contains a reaction product of a polyisocyanate component containing an aromatic polyisocyanate and a polyol component containing a crystalline macropolyol. Therefore, the polyurethane elastomer of the present invention has excellent mechanical properties.

In addition, in the polyurethane elastomer of the present invention, the curing agent contains a linear polyhydric alcohol containing oxygen and/or sulfur other than hydroxyl groups, and oxygen and/or sulfur other than hydroxyl groups is added to the total amount of the curing agent. The content ratio of the contained linear polyhydric alcohol is equal to or greater than a predetermined value. Therefore, the polyurethane elastomer of the present invention has an excellent pot life.

As a result, the polyurethane elastomer of the present invention has both excellent mechanical properties and an excellent pot life.

The polyurethane elastomer of the present invention is a cured urethane containing a reaction product of an isocyanate group-terminated prepolymer and a curing agent (described later).

The isocyanate group-terminated prepolymer includes a reaction product of a polyisocyanate component and a polyol component. Preferably, the isocyanate group-terminated prepolymer is the reaction product of a polyisocyanate component and a polyol component.

The polyisocyanate component contains aromatic polyisocyanate as an essential component. Aromatic polyisocyanates include, for example, aromatic polyisocyanate monomers and aromatic polyisocyanate derivatives.

Examples of aromatic polyisocyanate monomers include aromatic diisocyanates. Aromatic diisocyanates include, for example, tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), toluidine diisocyanate (TODI), paraphenylene diisocyanate, and naphthalene diisocyanate (NDI). These can be used alone or in combination of two or more.

Examples of aromatic polyisocyanate derivatives include modified products obtained by modifying the above aromatic polyisocyanate monomers by known methods. Modifications include, for example, uretdione modifications, isocyanurate modifications, allophanate modifications, polyol modifications, biuret modifications, urea modifications, oxadiazinetrione modifications and carbodiimide modifications. Aromatic polyisocyanate derivatives also include polymethylene polyphenylene polyisocyanate (p-MDI). These can be used alone or in combination of two or more.

The aromatic polyisocyanate preferably includes an aromatic polyisocyanate monomer, more preferably an aromatic diisocyanate, and still more preferably diphenylmethane diisocyanate (MDI) and naphthalene diisocyanate (NDI). and particularly preferably diphenylmethane diisocyanate (MDI).

Thus, the aromatic polyisocyanate preferably comprises diphenylmethane diisocyanate, particularly preferably consists of diphenylmethane diisocyanate. If the aromatic polyisocyanate contains diphenylmethane diisocyanate, it is possible to obtain a polyurethane elastomer particularly excellent in mechanical properties.

Diphenylmethane diisocyanates (MDI) include, for example, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate and 2,2'-diphenylmethane diisocyanate. These can be used alone or in combination of two or more. Diphenylmethane diisocyanate (MDI) preferably includes 4,4'-diphenylmethane diisocyanate.

The polyisocyanate component can optionally contain other polyisocyanates as long as they do not impair the excellent effects of the present invention. Other polyisocyanates are polyisocyanates other than aromatic polyisocyanates. Other polyisocyanates more specifically include aliphatic polyisocyanates and araliphatic polyisocyanates.

Aliphatic polyisocyanates include, for example, chain aliphatic polyisocyanates and alicyclic polyisocyanates.

Chain aliphatic polyisocyanates include, for example, chain aliphatic polyisocyanate monomers and chain aliphatic polyisocyanate derivatives. Chain aliphatic polyisocyanate monomers include, for example, chain aliphatic diisocyanates. Chain aliphatic diisocyanates include, for example, ethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate (PDI) and hexamethylene diisocyanate (HDI). Examples of chain aliphatic polyisocyanate derivatives include the modified chain aliphatic polyisocyanate monomers described above.

Alicyclic polyisocyanates include, for example, alicyclic polyisocyanate monomers and alicyclic polyisocyanate derivatives. Alicyclic polyisocyanate monomers include, for example, alicyclic diisocyanates. Alicyclic diisocyanates include, for example, isophorone diisocyanate (IPDI), norbornene diisocyanate ( _NBDI ), methylenebis(cyclohexylisocyanate) ( _H12MDI ), and bis(isocyanatomethyl)cyclohexane (H6XDI). Examples of alicyclic polyisocyanate derivatives include the above modified alicyclic polyisocyanate monomers.

Araliphatic polyisocyanates include, for example, araliphatic polyisocyanate monomers and araliphatic polyisocyanate derivatives. Examples of araliphatic polyisocyanate monomers include araliphatic diisocyanates. Araliphatic diisocyanates include, for example, xylylene diisocyanate (XDI) and tetramethylxylylene diisocyanate (TMXDI). Examples of the araliphatic polyisocyanate derivative include the above modified araliphatic polyisocyanate monomers.

Other polyisocyanate monomers can be used alone or in combination of two or more. From the viewpoint of mechanical properties, the content of other polyisocyanates is, for example, 50% by mass or less, preferably 30% by mass or less, more preferably 20% by mass or less, more preferably 20% by mass or less, with respect to the total amount of the polyisocyanate component. is 10% by mass or less, particularly preferably 0% by mass.

That is, the content of the aromatic polyisocyanate is, from the viewpoint of mechanical properties, relative to the total amount of the polyisocyanate component, for example, 50% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, More preferably 90 mass % or more, particularly preferably 100 mass %. Thus, the polyisocyanate component particularly preferably consists of aromatic polyisocyanates.

The polyol component contains macropolyol, preferably consists of macropolyol. A macropolyol is an organic compound having two or more hydroxyl groups in its molecule and having a relatively high molecular weight. The number average molecular weight of the macropolyol is, for example, over 300, preferably 400 or more, more preferably 1000 or more. In addition, the number average molecular weight of the macropolyol is, for example, 5000 or less, preferably 4000 or less, more preferably 3000 or less, still more preferably 2000 or less. Moreover, the average number of functional groups (average number of hydroxyl groups) of the macropolyol is, for example, 2 or more. Also, the average number of functional groups (average number of hydroxyl groups) of the macropolyol is, for example, 6 or less, preferably 4 or less, more preferably 3 or less. The average number of functional groups (average number of hydroxyl groups) of the macropolyol is particularly preferably two.

A macropolyol contains a crystalline macropolyol as an essential component. Crystallinity means being solid at room temperature (20°C).

More specific examples of crystalline macropolyols include crystalline polyether polyols, crystalline polyester polyols and crystalline polycarbonate polyols.

Crystalline polyether polyols include, for example, crystalline polyoxyalkylene polyols. Crystalline polyoxyalkylene polyols include, for example, crystalline polytetramethylene ether polyols.

Examples of crystalline polyester polyols include crystalline condensation polyester polyols and crystalline ring-opening polyester polyols. Examples of condensation polyester polyols include adipate polyester polyols obtained by a condensation reaction between a linear alcohol and adipic acid, and terephthalate polyester polyols obtained by a condensation reaction between a linear alcohol and terephthalic acid. be done. Examples of ring-opening polyester polyols include lactone polyester polyols.

Crystalline polycarbonate polyols include, for example, ring-opening polymers of ethylene carbonate using a known low-molecular-weight polyol as an initiator.

These crystalline macropolyols can be used alone or in combination of two or more. Crystalline macropolyols preferably include crystalline polyester polyols and crystalline polycarbonate polyols.

Also, the crystalline macropolyol preferably includes a macropolyol having a relatively high melting point. The melting point is, for example, the peak top temperature of the endothermic peak observed by raising the temperature of the macropolyol from −100° C. to 120° C. at 10° C./min in differential scanning calorimetry according to Examples described later.

The melting point of the crystalline macropolyol is, for example, 20°C or higher, preferably 30°C or higher, more preferably 50°C or higher, still more preferably 52°C or higher, and for example, 100°C or lower, preferably 80°C. It is below.

The macropolyol can optionally contain an amorphous macropolyol. Amorphous means that it is liquid (that is, liquid or fluid) at room temperature (20° C.).

As the amorphous macropolyol, more specifically, for example, amorphous polyether polyol, amorphous polyester polyol, amorphous polycarbonate polyol, amorphous polyurethane polyol, amorphous epoxy polyol, amorphous vegetable oil Examples include polyols, amorphous polyolefin polyols, amorphous acrylic polyols, and amorphous vinyl monomer-modified polyols.

Amorphous macropolyols can be used alone or in combination of two or more. From the viewpoint of mechanical strength, the content of the amorphous macropolyol is, for example, 50% by mass or less, preferably 30% by mass or less, more preferably 20% by mass or less, more preferably 20% by mass or less, relative to the total amount of the polyol component. is 10% by mass or less, particularly preferably 0% by mass.

That is, from the viewpoint of mechanical strength, the content of the crystalline macropolyol is, for example, 50% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, relative to the total amount of the polyol component. It is preferably 90% by mass or more, particularly preferably 100% by mass. That is, the polyol component particularly preferably consists of crystalline macropolyols.

An isocyanate group-terminated prepolymer is obtained, for example, by reacting a polyisocyanate component and a polyol component in a predetermined ratio (prepolymer step).

The blending ratio of the polyisocyanate component and the polyol component is adjusted so that the isocyanate groups are excessive relative to the hydroxyl groups. More specifically, the equivalent ratio of isocyanate groups in the polyisocyanate component to hydroxyl groups in the polyol component (isocyanate groups/hydroxyl groups) is, for example, 1.5 or more, preferably 1.8 or more, more preferably 2 or more, more preferably 2.5 or more. Further, the equivalent ratio of the isocyanate groups in the polyisocyanate component to the hydroxyl groups in the polyol component (isocyanate groups/hydroxyl groups) is, for example, 10 or less, preferably 7 or less, more preferably 6 or less, and still more preferably 5. It is below.

Polymerization methods include, for example, bulk polymerization and solution polymerization. In bulk polymerization, for example, the polyisocyanate component and the polyol component are reacted under a stream of nitrogen. The reaction temperature is, for example, 50° C. or higher. Also, the reaction temperature is, for example, 250° C. or lower, preferably 200° C. or lower. Also, the reaction time is, for example, 0.5 hours or longer, preferably 1 hour or longer. Also, the reaction time is, for example, 15 hours or less. In solution polymerization, a polyisocyanate component and a polyol component are reacted in the presence of a known organic solvent. The reaction temperature is, for example, 50° C. or higher. Also, the reaction temperature is, for example, 120° C. or lower, preferably 100° C. or lower. Also, the reaction time is, for example, 0.5 hours or longer, preferably 1 hour or longer. Also, the reaction time is, for example, 15 hours or less.

Also, if necessary, a known urethanization catalyst can be added. Urethane-forming catalysts include, for example, amines and organometallic compounds. The addition ratio of the urethanization catalyst is appropriately set according to the purpose and application.

Thereby, a reaction mixture containing an isocyanate group-terminated prepolymer is obtained. The isocyanate group concentration of the reaction mixture is, for example, 1% by mass or more, preferably 3% by mass or more, more preferably 4% by mass or more. Further, the isocyanate group concentration of the reaction mixture is, for example, 30% by mass or less, preferably 19% by mass or less, more preferably 16% by mass or less, even more preferably 15% by mass or less, still more preferably 10% by mass. It is below. The isocyanate group concentration (isocyanate group content) can be determined by a known method such as titration with di-n-butylamine or FT-IR analysis.

Moreover, the reaction mixture obtained by the above reaction can contain an unreacted polyisocyanate component (isocyanate monomer) in addition to the isocyanate group-terminated prepolymer. Unreacted polyisocyanate components are removed from the reaction mixture, if desired, by known removal methods. Moreover, the urethanization catalyst and the organic solvent are removed from the reaction mixture by a known removal method, if necessary. Removal methods include, for example, distillation and extraction.

Then, the polyurethane elastomer is produced by reacting the isocyanate group-terminated prepolymer with a curing agent (chain elongation step).

The curing agent contains, as an essential component, a linear polyhydric alcohol containing oxygen and/or sulfur other than hydroxyl groups.

In other words, the curing agent contains at least one selected from the group consisting of linear polyhydric alcohols containing oxygen other than hydroxyl groups and linear polyhydric alcohols containing sulfur.

A linear polyhydric alcohol is a relatively low-molecular-weight organic compound having two or more hydroxyl groups (--OH) in the molecule. A linear polyhydric alcohol does not have a branched chain and has a linear structure. The linear polyhydric alcohol has a molecular weight of, for example, 300 or less, preferably 250 or less. Moreover, the linear polyhydric alcohol has a molecular weight of, for example, 50 or more. Moreover, the average number of functional groups (average number of hydroxyl groups) of the linear polyhydric alcohol is, for example, 2 or more. The average number of functional groups (average number of hydroxyl groups) of the linear polyhydric alcohol is, for example, 6 or less, preferably 4 or less, more preferably 3 or less. The average number of functional groups (average number of hydroxyl groups) of the linear polyhydric alcohol is particularly preferably two.

Linear polyhydric alcohols containing oxygen other than hydroxyl groups are linear polyhydric alcohols containing oxygen atoms (O) other than oxygen atoms contained in hydroxyl groups (--OH) in the molecule.

Oxygen atoms (O) other than oxygen atoms contained in hydroxyl groups (--OH) are contained in linear polyhydric alcohols, for example, as oxygen-containing bonds. Examples of bonds include ether bond (-O-), carbonyl bond (-(C=O)-), ester bond (-O(C=O)-) and carbonate bond (-O-(C=O) -O-). These can be used alone or in combination of two or more. The bond is preferably an ether bond (--O--).

In addition, linear polyhydric alcohols containing oxygen other than hydroxyl groups preferably do not contain sulfur atoms. Linear polyhydric alcohols containing oxygen other than hydroxyl groups more preferably do not contain heteroatoms other than oxygen. That is, linear polyhydric alcohols containing oxygen other than hydroxyl groups preferably contain only oxygen as heteroatoms.

As linear polyhydric alcohols containing oxygen other than hydroxyl groups, more specifically, diethylene glycol, triethylene glycol, and bis(3-hydroxypropyl) ether (also known as di(1,3-propylene glycol)) is mentioned. These can be used alone or in combination of two or more.

As the linear polyhydric alcohol containing oxygen other than hydroxyl group, diethylene glycol is preferred. With diethylene glycol, a polyurethane elastomer having both superior mechanical properties and a superior pot life can be obtained.

A sulfur-containing linear polyhydric alcohol is an organic compound having two or more hydroxyl groups in the molecule and containing a sulfur atom (S) in the molecule. In addition, the sulfur-containing linear polyhydric alcohol may further contain oxygen atoms (O) other than the oxygen atoms contained in the hydroxyl groups (--OH).

Sulfur atoms are included in linear polyhydric alcohols, for example, as sulfur-containing bonds. Examples of bonds include thioether bond (-S-), thiocarbonyl bond (-(C=S)-), thioester bond (-S(C=O)-) and thiocarbonate bond (-S-(C= S)-S-). These can be used alone or in combination of two or more. The bond preferably includes a thioether bond (--S--).

Sulfur-containing linear polyhydric alcohols more specifically include 2,2'-thiodiethanol and bis(3-hydroxypropyl) thioether. These can be used alone or in combination of two or more.

As the sulfur-containing linear polyhydric alcohol, 2,2'-thiodiethanol is preferred.

These linear polyhydric alcohols containing oxygen and/or sulfur other than hydroxyl groups can be used alone or in combination of two or more.

An excellent pot life can be obtained by using a linear polyhydric alcohol containing oxygen and/or sulfur other than hydroxyl groups.

That is, since oxygen and/or sulfur other than hydroxyl groups have relatively high electronegativity, electron withdrawal of oxygen and/or sulfur reduces the reactivity of hydroxyl groups at the ends of molecules. Therefore, by using a linear polyhydric alcohol containing oxygen and / or sulfur other than hydroxyl groups, compared to the case where no polyhydric alcohol containing oxygen and / or sulfur other than hydroxyl groups is used, a relatively long pot can gain life.

In addition, since oxygen and/or sulfur other than hydroxyl groups have relatively large atomic radii (covalent bond radius of single bond), steric hindrance by oxygen and/or sulfur may cause It reduces the reactivity of hydroxyl groups. Therefore, by using a linear polyhydric alcohol containing oxygen and / or sulfur other than hydroxyl groups, compared to the case where no polyhydric alcohol containing oxygen and / or sulfur other than hydroxyl groups is used, a relatively long pot can gain life.

In addition, linear polyhydric alcohols containing oxygen and/or sulfur other than hydroxyl groups are preferably linear polyhydric alcohols containing oxygen other than hydroxyl groups.

More specifically, the electronegativity of oxygen (Pauling's electronegativity) is 3.44. The electronegativity of sulfur (Pauling's electronegativity) is 2.58. Therefore, from the viewpoint of reducing the reactivity of the hydroxyl group at the end of the molecule due to electron withdrawal, the oxygen and/or sulfur is preferably oxygen with higher electronegativity.

Also, the atomic radius of oxygen (covalent bond radius of a single bond) is 63 pm. Also, the atomic radius of sulfur (the covalent radius of a single bond) is 103 pm. Therefore, from the viewpoint of reducing the reactivity of hydroxyl groups at the ends of molecules due to steric hindrance, sulfur having a larger atomic radius is preferred as oxygen and/or sulfur.

In addition, linear polyhydric alcohols containing oxygen and/or sulfur other than hydroxyl groups are preferably linear polyhydric alcohols containing oxygen other than hydroxyl groups. Linear polyhydric alcohols containing oxygen other than hydroxyl groups do not contain sulfur. Therefore, if the linear polyhydric alcohol containing oxygen and/or sulfur other than hydroxyl groups is a linear polyhydric alcohol containing oxygen other than hydroxyl groups, no odor due to sulfur is generated, and workability is improved. can be planned.

The content of the linear polyhydric alcohol containing oxygen other than hydroxyl groups relative to the total amount of linear polyhydric alcohols containing oxygen and/or sulfur other than hydroxyl groups is, for example, 10% by mass or more, preferably , 20% by mass or more, more preferably 50% by mass or more, still more preferably 80% by mass or more, and particularly preferably 100% by mass. In other words, the linear polyhydric alcohol containing oxygen and/or sulfur other than hydroxyl groups is particularly preferably a linear polyhydric alcohol containing oxygen other than hydroxyl groups.

The curing agent can also contain other polyhydric alcohols as optional components. Other polyhydric alcohols are polyhydric alcohols excluding linear polyhydric alcohols containing oxygen and/or sulfur other than hydroxyl groups.

The molecular weight of other polyhydric alcohols is, for example, 300 or less, preferably 250 or less. Moreover, the molecular weight of other polyhydric alcohols is, for example, 50 or more. Moreover, the average number of functional groups (average number of hydroxyl groups) of other polyhydric alcohols is, for example, 2 or more. Further, the average number of functional groups (average number of hydroxyl groups) of other polyhydric alcohols is, for example, 6 or less, preferably 4 or less, more preferably 3 or less. The average number of functional groups (average number of hydroxyl groups) of other polyhydric alcohols is particularly preferably two.

Other polyhydric alcohols include, for example, branched polyhydric alcohols containing oxygen and/or sulfur other than hydroxyl groups, and more specifically, for example, dipropylene glycol (also known as di(1,2- propylene glycol)), and diglycerin. These can be used alone or in combination of two or more.

Other polyhydric alcohols include, for example, polyhydric alcohols containing no oxygen and/or sulfur other than hydroxyl groups, more specifically, linear polyhydric alcohols containing no oxygen and/or sulfur other than hydroxyl groups Examples include polyhydric alcohols and branched polyhydric alcohols containing no oxygen and/or sulfur other than hydroxyl groups. Linear polyhydric alcohols containing no oxygen and/or sulfur other than hydroxyl groups include, for example, ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 1, 6-hexanediol is mentioned. Examples of branched polyhydric alcohols containing no oxygen and/or sulfur other than hydroxyl groups include 1,2-propanediol, 1,2-butanediol, 1,3-butanediol, neopentyl glycol, glycerin, and trimethylol. Propane and pentaerythritol are included. These can be used alone or in combination of two or more.

Other polyhydric alcohols can be used alone or in combination of two or more. The content of other polyhydric alcohols is 80% by mass or less, preferably 60% by mass or less, more preferably 40% by mass or less, still more preferably 20% by mass or less, based on the total amount of the curing agent. Preferably, it is 10% by mass or less.

That is, the content of the linear polyhydric alcohol containing oxygen and/or sulfur other than hydroxyl groups is 20% by mass or more, preferably 40% by mass or more, more preferably 60% by mass, relative to the total amount of the curing agent. % by mass or more, more preferably 80% by mass or more, more preferably 90% by mass or more.

When the content of the linear polyhydric alcohol containing oxygen and/or sulfur other than hydroxyl groups is within the above range, a polyurethane elastomer having both excellent mechanical properties and an excellent pot life can be obtained.

The content of the linear polyhydric alcohol containing oxygen and/or sulfur other than hydroxyl groups is particularly preferably 100% by mass relative to the total amount of the curing agent. In other words, the curing agent particularly preferably consists of a linear polyhydric alcohol containing oxygen and/or sulfur other than hydroxyl groups. When the curing agent consists of a linear polyhydric alcohol containing oxygen and/or sulfur other than acid groups, a polyurethane elastomer having particularly excellent mechanical properties and a particularly excellent pot life can be obtained.

In the reaction between the isocyanate group-terminated prepolymer and the curing agent, the mixing ratio of the isocyanate group-terminated prepolymer and the curing agent is appropriately set according to the purpose and application. For example, the equivalent ratio of the hydroxyl group of the curing agent to the isocyanate group in the isocyanate group-terminated prepolymer (hydroxyl group/isocyanate group) is, for example, 0.75 or more, preferably 0.85 or more, for example, 1.3 or less, Preferably, it is 1.2 or less.

In addition, bulk polymerization and/or solution polymerization, for example, is employed in the reaction between the isocyanate group-terminated prepolymer and the curing agent. The reaction temperature is, for example, room temperature or higher, preferably 50° C. or higher. Moreover, the reaction temperature is, for example, 200° C. or lower, preferably 150° C. or lower. Also, the reaction time is, for example, 5 minutes or longer, preferably 1 hour or longer. Also, the reaction time is, for example, 72 hours or less, preferably 48 hours or less. At the time of mixing the isocyanate group-terminated prepolymer and the curing agent, a urethanization catalyst can be added in an appropriate proportion, if necessary.

Thereby, a polyurethane elastomer containing a reaction product of an isocyanate group-terminated prepolymer and a curing agent is obtained.

Also preferably, the mixture of the isocyanate group-terminated prepolymer and the curing agent is defoamed as necessary, cured in a preheated mold, and demolded. Thereby, a polyurethane elastomer molded into a desired shape is obtained.

Polyurethane elastomers can also be heat treated. The heat treatment temperature is, for example, 50° C. or higher, preferably 80° C. or higher. Also, the heat treatment temperature is, for example, 200° C. or lower, preferably 150° C. or lower. Also, the heat treatment time is, for example, 30 minutes or longer, preferably 1 hour or longer. Also, the heat treatment time is, for example, 30 hours or less, preferably 20 hours or less.

Also, the polyurethane elastomer can be cured. The curing temperature is, for example, 10°C or higher, preferably 20°C or higher. Also, the curing temperature is, for example, 50° C. or lower, preferably 40° C. or lower. Also, the curing time is, for example, 1 hour or longer, preferably 10 hours or longer. Also, the curing time is, for example, 20 days or less, preferably 10 days or less.

The polyurethane elastomer may optionally contain known additives in addition to the reaction product of the isocyanate group-terminated prepolymer and the curing agent. That is, the polyurethane elastomer may be a polyurethane elastomer composition.

Additives include, for example, antioxidants, heat stabilizers, ultraviolet absorbers, light stabilizers, antiblocking agents, release agents, pigments, dyes, lubricants, fillers, hydrolysis inhibitors, rust inhibitors, and bluing. agents. The amount and timing of addition of the additive are appropriately set according to the purpose and application. For example, the additive may be added to the isocyanate group-terminated prepolymer. Also, the additive may be added to the curing agent. Furthermore, the additive may be prepared separately from the isocyanate group-terminated prepolymer and the curing agent and added when the isocyanate group-terminated prepolymer and the curing agent are mixed.

The above polyurethane elastomer has both excellent mechanical properties and an excellent pot life.

That is, in the above polyurethane elastomer, the curing agent contains a linear polyhydric alcohol containing oxygen and/or sulfur other than hydroxyl groups, and oxygen and/or sulfur other than hydroxyl groups is contained relative to the total amount of the curing agent. The content ratio of the linear polyhydric alcohol is a predetermined value or more. Therefore, the above polyurethane elastomer has an excellent pot life.

On the other hand, since linear polyhydric alcohols containing oxygen and/or sulfur other than hydroxyl groups contain oxygen and/or sulfur other than hydroxyl groups, compared to polyhydric alcohols composed of hydroxyl groups and hydrocarbons that do not contain these, , reduces the crystallinity of the hard segment of the polyurethane elastomer. Therefore, the mechanical properties of the polyurethane elastomer may be inferior.

However, in the above polyurethane elastomer, the isocyanate group-terminated prepolymer contains a reaction product of a polyisocyanate component containing an aromatic polyisocyanate and a polyol component containing a crystalline macropolyol. That is, the polyol component contains a crystalline macropolyol. Therefore, the crystalline macropolyol improves the crystallinity of the soft segment of the polyurethane elastomer.

In other words, the crystalline macropolyol supplements the crystallinity that has been lowered by the linear polyhydric alcohol containing oxygen and/or sulfur other than hydroxyl groups. Therefore, the above polyurethane elastomer has excellent mechanical properties. As a result, the above polyurethane elastomer has both excellent mechanical properties and an excellent pot life.

Polyurethane elastomers are manufactured as TPU (Thermoplastic Polyurethane Resin) or TSU (Thermoset Polyurethane Resin). Preferably, the polyurethane elastomer is manufactured as TPU (thermoplastic polyurethane resin). A polyurethane elastomer is molded by a known molding method.

Examples of molding methods include cast molding, heat compression molding, injection molding, extrusion molding, and melt spinning molding. Shapes after molding include, for example, pellets, plates, fibers, strands, films, sheets, pipes, bottles, hollows, boxes, and buttons.

Polyurethane elastomers are preferably cast molded. That is, the polyurethane elastomer is preferably a cast polyurethane elastomer. Molded articles of polyurethane elastomer are articles that have a predetermined shape by themselves according to the purpose and application, and are distinguished from coating agents that are applied to objects to be coated. Polyurethane elastomers and moldings have excellent mechanical strength. For example, the tear strength of the polyurethane elastomer and molded article (according to Examples described later) is, for example, 50 kN/m or more. Furthermore, such molded articles are excellent in pot life. Therefore, molded articles are suitably used in various industrial fields.

Applications of molded products include, for example, transparent hard plastics, waterproof materials, sheets, bands, belts, tubes, blades, speakers, sensors, outsoles, threads, fibers, non-woven fabrics, cosmetics, shoe supplies, heat insulating materials, and sealing materials. , tape materials, sealing materials, photovoltaic power generation components, robot components, android components, wearable components, clothing products, sanitary products, cosmetic products, furniture products, food packaging components, sporting goods, leisure products, medical products, nursing care products, Housing materials, acoustic materials, lighting materials, anti-vibration materials, sound insulation materials, daily necessities, miscellaneous goods, cushions, bedding, stress absorbing materials, stress relieving materials, automotive interior materials, automotive exterior materials, railway materials, aircraft materials, optical materials, OA equipment parts, miscellaneous surface protection materials, semiconductor sealing materials, self-healing materials, health equipment, eyeglass lenses, toys, packing, cable sheaths, wire harnesses, telecommunication cables, automotive wiring, computer wiring, industrial products, shock absorption materials and semiconductor supplies.

Next, the present invention will be described based on Examples and Comparative Examples, but the present invention is not limited by these. "Parts" and "%" are based on mass unless otherwise specified. In addition, specific numerical values such as the mixing ratio (content ratio), physical property values, and parameters used in the following description are the corresponding mixing ratios ( content ratio), physical properties, parameters, etc. be able to.

1. Raw material <Polyisocyanate component>
1) 4,4'-MDI: 4,4'-diphenylmethane diisocyanate, trade name: Cosmonate PH, manufactured by Mitsui Chemicals SKC 2) 1,5-NDI: 1,5-naphthalenediisocyanate 3) 1,4-H ₆ XDI: 1,4-bis(isocyanatomethyl)cyclohexane synthesized by the method described in Production Example 3 of International Publication WO2019/069802, trans 86 mol%

<Macropolyol component>
1) UH-200W: crystalline polycarbonate polyol (PCD), number average molecular weight (Mn) 2000, trade name; ETERNACOL UH-200W, hydroxyl value = 56.1 mgKOH/g, melting point 53°C, room temperature solid, manufactured by Ube Industries, Ltd. 2) PES4040: Crystalline polyester polyol (polyethylene adipate polyol, PEA), number average molecular weight (Mn) 2000, trade name: Nippolan 4040, hydroxyl value = 56.1 mgKOH/g, melting point 51°C, solid at room temperature, manufactured by Tosoh Corporation 3 ) PTMG1000: Crystalline polyether polyol (polytetramethylene ether glycol, PTMEG), number average molecular weight (Mn) 1000, trade name; PTMG1000, hydroxyl value = 112.2 mgKOH/g, melting point 23°C, room temperature solid, Mitsubishi Chemical Corporation 4) T5652: amorphous polycarbonate polyol (PCD), number average molecular weight (Mn) 2000, trade name: Duranol T5652, hydroxyl value = 56.1 mgKOH/g, normal temperature liquid, manufactured by Asahi Kasei 5) D2000: amorphous Polyether polyol (polypropylene glycol, PPG), number average molecular weight (Mn) 2000, trade name; Actcol D2000, hydroxyl value = 56.1 mgKOH/g, normal temperature liquid, manufactured by Mitsui Chemicals SKC Co., Ltd.

<Curing agent>
1) Diethylene glycol: DEG, linear polyhydric alcohol containing oxygen other than hydroxyl group 2) 2,2'-Thiodiethanol: linear polyhydric alcohol containing sulfur 3) Dipropylene glycol: DPG, other than hydroxyl group Oxygen-containing branched polyhydric alcohol 4) 1,4-butanediol: 1,4-BD, a linear polyhydric alcohol containing no oxygen and sulfur other than hydroxyl groups

<Additive>
1) Heat resistant stabilizer: trade name; JPP100, manufactured by Johoku Chemical Industry Co., Ltd. 2) Antifoaming agent: trade name; BYK-088, manufactured by BYK Chemie Japan 3) Solvent: diisononyl adipate, trade name: DINA, Daihachi Chemical Industry manufactured by the company

2. Production Examples 1-7 and Comparative Examples 1-6
<Production of isocyanate group-terminated prepolymer>
According to the formulations shown in Tables 1 and 2, the polyisocyanate component and the polyol component were placed in a four-necked flask equipped with a reflux condenser, a nitrogen inlet tube, a thermometer and a stirrer. After that, 0.1 parts by mass of JPP100, 0.2 parts by mass of BYK-088 and 0.1 parts by mass of o-toluenesulfonamide were added. The reaction was carried out at 80° C. under a nitrogen atmosphere. Also, the reaction was stopped when the isocyanate group content of these mixtures reached the values shown in the table. Thus, an isocyanate group-terminated prepolymer was obtained. Tables 1 and 2 show the equivalent ratio of active hydrogen groups to isocyanate groups (NCO/active hydrogen groups) in the above reaction (prepolymerization reaction).

In Comparative Example 6, dibutyltin dilaurate, which had been diluted with DINA to 2% by mass in advance, was added to the four-necked flask together with the polyisocyanate component and the polyol component. The amount of dibutyltin dilaurate added was adjusted to 10 ppm.

<Production of Polyurethane Elastomer>
An isocyanate group-terminated prepolymer and a curing agent were mixed at 80° C. at a ratio such that the equivalent ratio (OH/NCO) was 0.95, followed by stirring and vacuum defoaming. These mixtures were poured into a mold (sheet shape with a thickness of 2 mm) preheated to 110° C. and cured in an oven at 110° C. for 2 hours to obtain a polyurethane elastomer. Also, the polyurethane elastomer was demolded from the mold. Thereafter, the polyurethane elastomer was heat-treated in an oven at 110° C. for 15 hours, and then aged for 7 days under constant temperature and humidity conditions of room temperature of 23° C. and relative humidity of 55% to obtain a sheet-shaped polyurethane elastomer.

In Comparative Example 6, dibutyltin dilaurate, which had been diluted with DINA to 2% by mass in advance, was added to the isocyanate group-terminated prepolymer. The amount added was adjusted so that the added amount of dibutyltin dilaurate (not including the added amount in the production of the isocyanate group-terminated prepolymer) was 100 ppm.

Comparative Example 7 (one-shot method)
A polyisocyanate component, a polyol component and a curing agent were mixed at 80° C. in the proportions shown in Table 2, and the mixture was stirred and vacuum defoamed. These mixtures were poured into a mold (sheet shape with a thickness of 2 mm) preheated to 110° C. and cured in an oven at 110° C. for 2 hours to obtain a polyurethane elastomer. Also, the polyurethane elastomer was demolded from the mold. Thereafter, the polyurethane elastomer was heat-treated in an oven at 110° C. for 15 hours, and then aged for 7 days under constant temperature and humidity conditions of room temperature of 23° C. and relative humidity of 55% to obtain a sheet-shaped polyurethane elastomer.

3. Measurement <Isocyanate group concentration>
Using a potentiometric titrator, the isocyanate group concentration was measured by the n-dibutylamine method according to JIS K-1556 (2006).

<pot life>
An isocyanate group-terminated prepolymer and a curing agent were mixed at 80° C., and the time until the mixed liquid lost its fluidity after the start of mixing was evaluated in the following five stages.
Evaluation 5: The liquid mixture did not lose fluidity within 12 minutes after the start of mixing.
Rating 4: The mixture lost its fluidity more than 9 minutes and within 12 minutes after the start of mixing.
Rating 3: The mixture lost fluidity more than 6 minutes and within 9 minutes after mixing started.
Rating 2: The mixture lost its fluidity more than 3 minutes and within 6 minutes after the start of mixing.
Evaluation 1: Within 3 minutes after the start of mixing, the liquid mixture lost fluidity.

<Tear strength>
A right-angle tear test piece was prepared according to JIS K7311 (1995) from a sheet-shaped polyurethane elastomer (thickness of 2 mm), and the tear strength of the test piece was measured at a tensile speed of 500 mm/min.

<Melting point>
Using a differential scanning calorimeter (manufactured by SII Nanotechnology, trade name: EXSTAR6000 PC station and DSC220C), the melting point of the polyol component was measured by the following method.

The polyol component was collected in an aluminum pan. This gave a sample of the polyol component. Alumina was also collected in the same manner as the polyol component. As a result, alumina was used as a reference sample. After setting the sample and reference at a predetermined position in the cell, the sample was cooled to -100 ° C. at a rate of 10 ° C./min under a nitrogen stream with a flow rate of 40 NmL / min. The temperature was raised to 120°C at a rate of °C/min. The temperature of the endothermic peak appearing during this temperature rise was taken as the melting point of the polyol component.

Claims (5)

A polyurethane elastomer comprising a reaction product of an isocyanate-terminated prepolymer and a curing agent,
The isocyanate group-terminated prepolymer contains a reaction product of a polyisocyanate component containing an aromatic polyisocyanate and a polyol component containing a crystalline macropolyol,
The curing agent contains a linear polyhydric alcohol containing oxygen and / or sulfur other than hydroxyl groups,
The polyurethane elastomer, wherein the content of the linear polyhydric alcohol containing oxygen and/or sulfur other than hydroxyl groups is 20% by mass or more relative to the total amount of the curing agent. 2. The polyurethane elastomer of claim 1, wherein said aromatic polyisocyanate comprises diphenylmethane diisocyanate. The content of the linear polyhydric alcohol containing oxygen other than hydroxyl groups is 20% by mass or more with respect to the total amount of the linear polyhydric alcohols containing oxygen and/or sulfur other than hydroxyl groups. 3. The polyurethane elastomer according to Item 1 or 2. The polyurethane elastomer according to any one of claims 1 to 3, wherein said linear polyhydric alcohol containing oxygen and/or sulfur other than hydroxyl groups comprises diethylene glycol. 5. The content of the linear polyhydric alcohol containing oxygen and/or sulfur other than hydroxyl groups is 80% by mass or more relative to the total amount of the curing agent, according to any one of claims 1 to 4 The described polyurethane elastomer.