Thermoplastic polyurea and molded article

Abstract

A thermoplastic polyurea comprising an aliphatic diamine unit (A) that has a linear aliphatic hydrocarbon group and an aliphatic diamine unit (B) that has a C7-12 methyl-branched aliphatic hydrocarbon group on the main chain.

Description

Thermoplastic polyurea and moldings

[0001] The present invention relates to a thermoplastic polyurea and a molded article.

[0002] Polyurea has excellent heat resistance, mechanical strength, and chemical resistance, and is used in injection-molded products, fibers, coatings, etc. Conventional polyureas are produced by polymerization of urea and formaldehyde or polymerization of diisocyanate and diamine, but the polyureas obtained by conventional methods are polymers that are difficult to melt-process, whether they are thermosetting or thermoplastic. Therefore, there is a demand for the development of thermoplastic polyureas that can be easily melt-processed.

[0003] To solve the above problems, polymerization using urea and diamines has been proposed. For example, as the diamine component, two or more linear alkylene diamines having different carbon numbers (see, for example, Patent Document 1), a primary diamine having at least one alkyl group having no more than 3 carbon atoms on any carbon atom of a linear saturated hydrocarbon group having a specific carbon number (see, for example, Patent Document 2), and a mixed system of a primary diamine having at least one alkyl group having no more than 10 carbon atoms on any carbon atom of a linear saturated aliphatic hydrocarbon group having a specific carbon number and a linear alkylene diamine having a specific carbon number (see, for example, Patent Document 3) have been disclosed. By using the techniques described in Patent Documents 1 to 3, polyureas having excellent physical and chemical properties such as good mechanical properties, moldability, and dyeability have been developed.

[0004] However, a thermoplastic polyurea that has excellent chemical resistance and can suppress discoloration during melt molding has not yet been obtained.

[0005] Special Publication No. 36-2847 Publication No. 36-22150 Publication No. 36-20249

[0006] An object of the present invention is to provide a thermoplastic polyurea that has excellent chemical resistance and is capable of suppressing discoloration during melt molding, and a molded article containing the thermoplastic polyurea.

[0007] As a result of extensive investigations, the present inventors have found that a thermoplastic polyurea having excellent chemical resistance and capable of suppressing discoloration during melt molding can be obtained by containing aliphatic diamine units (A) having a linear aliphatic hydrocarbon group and aliphatic diamine units (B) having a methyl-branched aliphatic hydrocarbon group having 7 to 12 main chain carbon atoms, and have thus completed the present invention.

[0008] That is, the present invention is as follows: [1] to [7]. [1] A thermoplastic polyurea having aliphatic diamine units (A) having a linear aliphatic hydrocarbon group and aliphatic diamine units (B) having a methyl-branched aliphatic hydrocarbon group having 7 to 12 main chain carbon atoms. [2] The thermoplastic polyurea according to the above [1], in which the molar ratio (A / B) of the aliphatic diamine units (A) to the aliphatic diamine units (B) is 99 / 1 to 30 / 70. [3] The thermoplastic polyurea according to the above [1] or [2], in which the average number of carbon atoms in the linear aliphatic hydrocarbon group is 7 to 11. [4] The thermoplastic polyurea according to any of the above [1] to [3], in which the bonds between the aliphatic diamine units (A) and the aliphatic diamine units (B), the bonds between the aliphatic diamine units (A) and between the aliphatic diamine units (B) are urea bonds. [5] The thermoplastic polyurea according to any one of [1] to [4] above, wherein the carbonyl group in the urea bond of the thermoplastic polyurea is derived from urea. [6] The thermoplastic polyurea according to any one of [1] to [5] above, wherein the melting point is 220°C or less. [7] A molded article comprising the thermoplastic polyurea according to any one of [1] to [6] above.

[0009] According to the present invention, it is possible to provide a thermoplastic polyurea that has excellent chemical resistance and is capable of suppressing discoloration during melt molding, and a molded article containing the thermoplastic polyurea.

[0010] The following description is based on an example of an embodiment of the present invention. However, the embodiment described below is merely an example for embodying the technical concept of the present invention, and the present invention is not limited to the following description. In this specification, preferred embodiments are shown, but a combination of two or more of the individual preferred embodiments is also a preferred embodiment. For matters indicated by numerical ranges, when there are several numerical ranges, the lower and upper limits can be selectively combined to form a preferred embodiment. In this specification, when a numerical range is described as "XX to YY," it means "XX or more and YY or less." In this specification, "polymer" refers to thermoplastic polyurea, "structural unit" refers to "a unit constituting a polymer," and "aliphatic diamine unit" refers to "a structural unit derived from an aliphatic diamine." In this specification, "easily melt-formable" means that the number-average molecular weight (Mn) and weight-average molecular weight (Mw) are not too high, and the melt viscosity is not too high, making it easy to melt-form.

[0011] [Thermoplastic Polyurea] The thermoplastic polyurea of ​​the present invention has aliphatic diamine units (A) having a linear aliphatic hydrocarbon group (hereinafter may be referred to as "aliphatic diamine units (A)") and aliphatic diamine units (B) having a methyl-branched aliphatic hydrocarbon group having 7 to 12 main chain carbon atoms (hereinafter may be referred to as "aliphatic diamine units (B)"), and may further have other structural units as necessary.

[0012] In the thermoplastic polyurea of ​​the present invention, the bond between the aliphatic diamine unit (A) and the aliphatic diamine unit (B), the bond between the aliphatic diamine units (A) and between the aliphatic diamine units (B) are preferably urea bonds (—NH—C(═O)—NH—). The thermoplastic polyurea may contain bonds other than urea bonds as long as the effects of the present invention are not impaired.

[0013] The carbonyl group (-C(=O)-) in the urea bond (-NH-C(=O)-NH-) of the thermoplastic polyurea of ​​the present invention is not particularly limited and may be derived from any of urea, isocyanate, carbon dioxide, carbonate, and phosgene, but is preferably derived from urea from the viewpoints of productivity, raw material toxicity, and availability. Here, "derived from urea" does not necessarily mean derived from urea, but also includes derived from urea derivatives such as methylene diurea and ethylene diurea.

[0014] The thermoplastic polyurea of ​​the present invention can be obtained, for example, by a polycondensation reaction in which an aliphatic diamine having an aliphatic hydrocarbon group and urea or the like are reacted in approximately equal molar ratios, preferably in an inert gas atmosphere, with or without dissolution in a solvent such as water, phenol or meta-cresol, and then the reaction is completed while distilling off the solvent, if any. ２ NC(=O)-NH ２ ) is not included.

[0015] In the polycondensation reaction, the mixture is first heated at a relatively low temperature of 80 to 130°C to produce a low-degree condensate, temporarily halting the generation of ammonia, and then the temperature is gradually raised. At approximately 140 to 190°C, the generation of ammonia becomes active again. The temperature is controlled during this process, and any solvent present is distilled off, and the temperature is raised again. After the deammoniating reaction by heating is completed, the reaction is continued under reduced pressure at a temperature of approximately 200 to 280°C, allowing the polycondensation reaction to proceed smoothly and resulting in a linear copolymer.

[0016] In addition, a terminal blocking agent, additives, etc. may be added as a secondary raw material for the polycondensation reaction. Examples of terminal blocking agents include monoamines such as hexylamine, octylamine, cyclohexylamine, and aniline; and monocarboxylic acids such as acetic acid, lauric acid, and benzoic acid. These may be used alone or in combination of two or more. The amount of terminal blocking agent added is preferably 5 mol% or less relative to the aliphatic diamine compound. Examples of additives include antioxidants, antistatic agents, flame retardants, flame retardant auxiliaries, and heat stabilizers. These may be used alone or in combination of two or more.

[0017] The melting point of the thermoplastic polyurea of ​​the present invention is preferably 220°C or lower, more preferably 215°C or lower, and particularly preferably 210°C or lower, from the viewpoint of reducing discoloration during melt molding, while from the viewpoint of heat resistance, it is preferably 150°C or higher, more preferably 160°C or higher, and particularly preferably 170°C or higher. The melting point of the thermoplastic polyurea of ​​the present invention is preferably 150 to 220°C, more preferably 160 to 215°C, and particularly preferably 170 to 210°C. The melting point of the thermoplastic polyurea of ​​the present invention can be measured by the method used in the examples described below.

[0018] The arrangement order of the aliphatic diamine units (A), the aliphatic diamine units (B), and any other structural units in the thermoplastic polyurea of ​​the present invention is not particularly limited, and may be random, block, alternating, or the like.

[0019] The total of the aliphatic diamine units (A) and the aliphatic diamine units (B) relative to 100 mol% of all structural units (excluding bonding portions between structural units) in the thermoplastic polyurea is preferably 70 mol% or more, more preferably 80 mol% or more, particularly preferably 90 mol% or more, and most preferably 100 mol%. That is, it is preferable that no structural units other than the aliphatic diamine units (A) and the aliphatic diamine units (B) are present. The total of the aliphatic diamine units (A) and the aliphatic diamine units (B) relative to 100 mol% of all structural units (excluding bonding portions between structural units) in the thermoplastic polyurea can be measured, for example, by NMR. The ratio of the diamine units constituting the aliphatic diamine units (A), aliphatic diamine units (B), etc. is １In the H-NMR measurement, it is calculated from the integrated value of a peak at 0.6 to 1.2 ppm assigned to protons bonded to methyl branches of the aliphatic diamine unit (B), a peak at 1.2 to 2.0 ppm assigned to protons bonded to methylene chains of the aliphatic diamine unit (A) or the aliphatic diamine unit (B), and a peak at 2.0 to 3.0 ppm assigned to protons bonded to methylene chains adjacent to amino groups of the aliphatic diamine unit (A) or the aliphatic diamine unit (B). The term "bonding portion between structural units" refers to, for example, (1) when the structural units are two types, i.e., an aliphatic diamine unit (A) and an aliphatic diamine unit (B), three types of bonding portions: a bond between the aliphatic diamine unit (A) and the aliphatic diamine unit (B), a bond between the aliphatic diamine units (A), and a bond between the aliphatic diamine units (B); and (2) when the structural units are three types, i.e., an aliphatic diamine unit (A), an aliphatic diamine unit (B), and another structural unit, six types of bonding portions: a bond between the aliphatic diamine unit (A) and the aliphatic diamine unit (B), a bond between the aliphatic diamine unit (A) and another structural unit, a bond between the aliphatic diamine unit (B) and another structural unit, a bond between the aliphatic diamine units (A), a bond between the aliphatic diamine units (B), and a bond between the other structural units.

[0020] The weight average molecular weight (Mw) of the thermoplastic polyurea is preferably 10,000 or more from the viewpoints of chemical resistance and mechanical strength, and is preferably 100,000 or less from the viewpoint of melt moldability. The weight average molecular weight (Mw) of the thermoplastic polyurea is preferably 10,000 to 100,000. The weight average molecular weight (Mw) of the thermoplastic polyurea is the weight average molecular weight (Mw) converted into polymethyl methacrylate (manufactured by Resonac Corporation) measured using gel permeation chromatography (GPC) under the following measurement conditions. <Measurement conditions> Measurement device: HLC-8320GPC Columns: 1 TSKgel SUPER AW-H Guard Column manufactured by Tosoh Corporation 2 TSKgel SUPER AWM-H columns manufactured by Tosoh Corporation 1 TSKgel SUPER H-RC column manufactured by Tosoh Corporation Solvent: hexafluoroisopropanol containing 12 mM sodium trifluoroacetate Flow rate: 0.5 mL / min Measurement temperature: 40°C

[0021] The number average molecular weight (Mn) of the thermoplastic polyurea is preferably 2000 or more from the viewpoints of chemical resistance and mechanical strength, and is preferably 50000 or less from the viewpoint of melt moldability. The number average molecular weight (Mn) of the thermoplastic polyurea is preferably 2000 to 50000. The number average molecular weight (Mn) of the thermoplastic polyurea is the number average molecular weight (Mn) converted into polymethyl methacrylate (manufactured by Resonac Corporation) measured using gel permeation chromatography (GPC) under the following measurement conditions. <Measurement conditions> Measurement device: HLC-8320GPC Columns: 1 TSKgel SUPER AW-H Guard Column manufactured by Tosoh Corporation 2 TSKgel SUPER AWM-H columns manufactured by Tosoh Corporation 1 TSKgel SUPER H-RC column manufactured by Tosoh Corporation Solvent: hexafluoroisopropanol containing 12 mM sodium trifluoroacetate Flow rate: 0.5 mL / min Measurement temperature: 40°C

[0022] The molecular weight distribution (Mw / Mn) of the thermoplastic polyurea is preferably 1.1 or more from the viewpoint of ease of production, and is preferably 10 or less from the viewpoint of melt moldability. The molecular weight distribution (Mw / Mn) of the thermoplastic polyurea is preferably 1.1 to 10.

[0023] <Aliphatic diamine unit (A)> The aliphatic diamine unit (A) is a structural unit derived from an aliphatic diamine having a linear aliphatic hydrocarbon group, and may or may not further have groups other than the hydrocarbon group, as necessary. Here, the aliphatic diamine having a linear aliphatic hydrocarbon group refers to an aliphatic diamine in which amino groups are bonded to both ends of the linear aliphatic hydrocarbon group. The linear aliphatic hydrocarbon group refers to a straight-chain divalent aliphatic hydrocarbon group that does not have a branched chain. The linear aliphatic hydrocarbon group may be a saturated hydrocarbon group or an unsaturated hydrocarbon group, but is preferably a saturated hydrocarbon group. The linear aliphatic hydrocarbon group is preferably an unsubstituted hydrocarbon group containing only carbon and hydrogen.

[0024] Examples of aliphatic diamines having a linear aliphatic hydrocarbon group that constitute the aliphatic diamine unit (A) include 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine (1,5-pentamethylenediamine), 1,6-hexanediamine (1,6-hexamethylenediamine), 1,7-heptanediamine (1,7-heptamethylenediamine), 1,8-octanediamine (1,8-octamethylenediamine), 1,9-nonanediamine (1,9-nonamethylenediamine), 1,10-decanediamine (1,10-decamethylenediamine), 1,11-undecanediamine (1,11-undecamethylenediamine), and 1,12-dodecanediamine (1,12-dodecamethylenediamine). These may be used alone or in combination of two or more. Among these, from the viewpoint of achieving both reduced coloration during melt molding and chemical resistance, 1,7-heptanediamine (1,7-heptamethylenediamine), 1,8-octanediamine (1,8-octamethylenediamine), 1,9-nonanediamine (1,9-nonamethylenediamine), 1,10-decanediamine (1,10-decamethylenediamine), 1,11-undecanediamine (1,11-undecamethylenediamine), and 1,12-dodecanediamine (1,12-dodecamethylenediamine) are preferred, and 1,9-nonanediamine (1,9-nonamethylenediamine) is particularly preferred.

[0025] The aliphatic diamine unit (A) may be used alone or in combination of two or more. When two or more types of aliphatic diamine units (A) are used, the molar amount of the aliphatic diamine units (A) means the sum of the molar amounts of the respective aliphatic diamine units (A).

[0026] The average number of carbon atoms in the linear aliphatic hydrocarbon groups in the aliphatic diamine units (A) is not particularly limited, but from the viewpoint of achieving both improved chemical resistance of the thermoplastic polyurea and suppression of discoloration during melting, it is preferably 7 to 11, more preferably 8 to 10, and particularly preferably 9. The "average number of carbon atoms in the linear aliphatic hydrocarbon groups in the aliphatic diamine units (A)" is calculated from the molar ratio of each component in the aliphatic diamine (A), and for example, in Example 5 described below, it is calculated as 9 × 1 / (1 + 84) + 12 × 84 / (1 + 84) = 12. In calculating the average carbon number, any fraction after the decimal point is rounded off.

[0027] <Aliphatic diamine unit (B)> The aliphatic diamine unit (B) is a structural unit derived from an aliphatic diamine having a methyl-branched aliphatic hydrocarbon group having 7 to 12 main chain carbon atoms, and may or may not further have other groups as necessary.

[0028] The term "methyl-branched aliphatic hydrocarbon group" refers to a divalent aliphatic hydrocarbon group having a methyl group as a branched chain, and does not include branched aliphatic hydrocarbon groups having a methyl group as a branched chain and another branched chain (e.g., an ethyl group or a propyl group). By using a methyl group as the branched group in the aliphatic hydrocarbon group in the aliphatic diamine unit (B), rather than an ethyl group or a propyl group, the thermoplastic polyurea is more likely to aggregate and has improved crystallinity compared to when an ethyl group or a propyl group is used, thereby improving the chemical resistance of the thermoplastic polyurea. By setting the main chain carbon number of the aliphatic diamine unit (B) to a certain number or more, the aggregation-inhibiting effect of the branched group is reduced, thereby improving chemical resistance. Furthermore, the presence of a methyl branched group reduces crystallinity compared to when no branched group is used, enabling melt molding at low temperatures and reducing discoloration during melt molding.

[0029] Examples of the aliphatic diamine having a methyl-branched aliphatic hydrocarbon group having 7 to 12 carbon atoms in the main chain, which constitutes the aliphatic diamine unit (B), include 2-methyl-1,7-heptanediamine, 2-methyl-1,8-octanediamine, 2-methyl-1,9-nonanediamine, 2-methyl-1,10-decanediamine, 2-methyl-1,11-undecanediamine, 2-methyl-1,12-dodecanediamine, 1,3-dimethyl-1,8-octanediamine, 1,4-dimethyl-1,8-octanediamine, 2,4-dimethyl-1,8-octanediamine, 2,2,4-trimethyl-1,8-octanediamine, 2,4,4-trimethyl-1,8-octanediamine, etc. These may be used alone or in combination of two or more. Among these, from the viewpoint of achieving both chemical resistance and reduced discoloration during melt molding, 2-methyl-1,7-heptanediamine, 2-methyl-1,8-octanediamine, 2-methyl-1,9-nonanediamine, 2-methyl-1,10-decanediamine, and 2-methyl-1,11-undecanediamine are preferred, and 2-methyl-1,7-heptanediamine, 2-methyl-1,8-octanediamine, 2-methyl-1,9-nonanediamine, and 2-methyl-1,10-decanediamine are more preferred, with 2-methyl-1,8-octanediamine and 2-methyl-1,9-nonanediamine being particularly preferred.

[0030] The aliphatic diamine unit (B) may be used alone or in combination of two or more. When two or more types of aliphatic diamine units (B) are used, the molar amount of the aliphatic diamine units (B) means the sum of the molar amounts of the respective aliphatic diamine units (B).

[0031] The number of carbon atoms in the main chain of the aliphatic diamine unit (B) is not particularly limited as long as it is 7 to 12, but from the viewpoint of achieving both chemical resistance and reduced discoloration during melt molding, it is preferably 7 to 11, more preferably 7 to 10, and particularly preferably 8 to 9. When the methyl-branched aliphatic hydrocarbon group in the aliphatic diamine unit (B) has a main chain carbon number of 7 or more, it can maintain chemical resistance while suppressing discoloration during melt molding of the thermoplastic polyurea. On the other hand, when the main chain carbon number is 12 or less, it can improve the chemical resistance of the thermoplastic polyurea. The main chain carbon number of the aliphatic diamine unit (B) is the number of carbon atoms excluding the carbons in the methyl branches. For example, the main chain carbon number of "2-methyl-1,8-octanediamine" is "8."

[0032] The number of methyl groups in the branched chain may be one or two or more. The methyl-branched aliphatic hydrocarbon group may be a saturated hydrocarbon group or an unsaturated hydrocarbon group, but is preferably a saturated hydrocarbon group. The methyl-branched aliphatic hydrocarbon group is preferably an unsubstituted hydrocarbon group containing only carbon and hydrogen.

[0033] The molar ratio (A / B) of the aliphatic diamine unit (A) to the aliphatic diamine unit (B) is not particularly limited, but from the viewpoint of achieving both improved chemical resistance and suppression of coloration during melting, it is preferably 99 / 1 to 30 / 70, more preferably 95 / 5 to 45 / 55, even more preferably 90 / 10 to 60 / 40, and particularly preferably 90 / 10 to 80 / 20.

[0034] By concentrating either the aliphatic diamine units (A) or the aliphatic diamine units (B), the polyurea has the properties of a thermoplastic polyurea composed of only one diamine and has distinctive features. That is, within the preferred range of the molar ratio (A / B) of the aliphatic diamine units (A) to (B), the polyurea has better chemical resistance as the proportion of the aliphatic diamine units (A) increases, and the polyurea has a better effect of reducing discoloration during melt molding as the proportion of the aliphatic diamine units (B) increases.

[0035] The thermoplastic polyurea of ​​the present invention can be processed into a molded article described below by known molding methods such as injection molding and extrusion molding. It can also be processed into various films by known film-forming methods such as the T-die method, inflation method, and heat press method. A thermoplastic polyurea composition containing the thermoplastic polyurea of ​​the present invention and a viscosity stabilizer may also be processed into a molded article by the above molding methods.

[0036] The viscosity stabilizer is not particularly limited, and examples thereof include monobasic acids, alkylmonoamides, monoamines, and N-acylalkylenediamines.

[0037] [Molded Article] The molded article of the present invention comprises the thermoplastic polyurea of ​​the present invention. The molded article of the present invention refers to a molded article obtained by processing a composition comprising the thermoplastic polyurea of ​​the present invention into various molded articles by a known molding method such as injection molding, extrusion molding, T-die molding, inflation molding, or hot press. Applications of the molded article of the present invention include, for example, electric and electronic parts, automobile parts, industrial parts, household products, medical parts, fibers, films, sheets, tubes, hoses, blown molded parts, foam molded articles, and other molded articles of any shape.

[0038] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the examples and comparative examples, "%" and "parts" represent "% by mass" and "parts by mass", respectively, unless otherwise specified. The measurement methods and evaluation methods employed in the following examples and comparative examples are shown below.

[0039] [Melting Point (°C)] The melting point of the obtained polymer was measured by a differential scanning calorimeter according to the method described in JIS K7121: 2012. Specifically, under a nitrogen flow of 50 mL / min, the temperature was raised from 25°C to 240°C at a heating rate of 10°C / min, further held at 240°C for 5 minutes, then cooled to 25°C at 10°C / min, further held at 25°C for 5 minutes, and then heated to 240°C at 10°C / min. The temperature of the highest endothermic peak when this was done was taken as the polymer melting point.

[0040] [Chemical Resistance] A test was conducted in accordance with JIS K7114:2001. Specifically, the prepared dumbbell test specimens were conditioned at 23°C and 50% RH, and then immersed in 100 mL of solvent at 23°C for one week. After one week of immersion, the test specimens were removed from the solvent, and tensile properties were evaluated by a tensile test. Solvent resistance was evaluated according to the following criteria, using the retention calculated from the following formula 1 as an index. Methanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used as the solvent. Retention (%) = (tensile modulus after solvent immersion / tensile modulus before solvent immersion) × 100 (Formula 1) <Evaluation Criteria> A: Retention ≥ 60% B: 60% > retention ≥ 40% C: 40% > retention

[0041] [Coloration Suppression] The degree of coloration suppression of the pressed film was visually judged according to the following criteria: <Judgment Criteria> A: Colorless and transparent B: Slightly yellowed C: Clearly yellowed

[0042] [ １ H-NMR measurement] The mixture ratio of 2,2,4-trimethyl-1,6-hexanediamine / 2,4,4-trimethyl-1,6-hexanediamine mixture (manufactured by Tokyo Chemical Industry Co., Ltd.) was １ Specifically, an NMR measurement apparatus JMTC-40 / 54 / JJ / YH (manufactured by JEOL) was used, and the １ 5 mg of sample was dissolved in 1 mL of Sigma-Aldrich solution. The measurement conditions were set as follows: 16 accumulations, and a measurement temperature of 22°C. The mixing ratio was 2,2,4-trimethyl-1,6-hexanediamine:2,4,4-trimethyl-1,6-hexanediamine=35:65 [mol %], based on the integrated values ​​of the peaks at 2.4 to 2.5 ppm assigned to the protons bonded to the 1-position of 2,2,4-trimethyl-1,6-hexanediamine and the protons bonded to the 1-position of 2,4,4-trimethyl-1,6-hexanediamine, the peak at 2.5 to 2.6 ppm assigned to the protons bonded to the 1-position of 2,4,4-trimethyl-1,6-hexanediamine, and the peak at 2.6 to 2.8 ppm assigned to the protons bonded to the 6-positions of 2,2,4-trimethyl-1,6-hexanediamine and 2,4,4-trimethyl-1,6-hexanediamine.

[0043] Example 1 <Polymer Production> Urea (manufactured by Tokyo Chemical Industry Co., Ltd.), 1,9-nonanediamine, and 2-methyl-1,8-octanediamine were charged into a flask equipped with a device capable of distilling off generated liquids and gases, in a molar ratio of urea / 1,9-nonanediamine / 2-methyl-1,8-octanediamine = 50.0 / 42.5 / 7.5. Under a nitrogen flow at 50 mL / min, the mixture was heated from 25°C to 130°C and heated for 1 hour, then further heated to 160°C and heated for 1 hour. The mixture was further heated to 240°C and heated for 3 hours to obtain a colorless, transparent polymer. The resulting polymer had a number-average molecular weight of 5,200, a weight-average molecular weight of 14,200, and a molecular weight distribution of 2.7. The melting point of the resulting polymer was measured. The measurement results are shown in Table 1.

[0044] <Press film molding> The obtained polymer was compressed using a single-action compression molding machine (Imoto Manufacturing Co., Ltd., "IMC-183B"), reduced in pressure to -0.1 MPaG using an oil rotary pump, preheated at the melting point +20°C for 5 minutes, and pressed at 50 kN for 30 seconds. Thereafter, the film was cooled using a cooling press equipped with water flow cooling and pressed at 70 kgf / cm. ２ The film was pressed at 100°C for 5 minutes to prepare a pressed film having a thickness of 125 μm. The prepared pressed film was evaluated for color inhibition. The evaluation results are shown in Table 1.

[0045] <Preparation of Dumbbell Test Pieces> The obtained polymer was used in a small kneader ("MC15-HT" manufactured by XPLORE INSTRUMENTS) at a stirring speed of 50 rpm, a kneading temperature of the melting point + 40°C, and a mold temperature of the melting point - 60°C to prepare small test pieces type 1BA. The resulting dumbbell test pieces were subjected to crystallization treatment in a 110°C thermostatic bath for 6 hours to obtain dumbbell test pieces. The chemical resistance of the obtained dumbbell test pieces was evaluated. The evaluation results are shown in Table 1.

[0046] Example 2 Polymer production, press film molding, and dumbbell test specimen preparation were carried out in the same manner as in Example 1, except that the molar ratio of urea to 1,9-nonanediamine to 2-methyl-1,8-octanediamine in the polymer production was changed from 50.0 / 42.5 / 7.5 to 50.0 / 32.5 / 17.5. The number-average molecular weight of the obtained polymer was 6,500, the weight-average molecular weight was 14,500, and the molecular weight distribution was 2.2. The obtained measurement results and evaluation results are shown in Table 1.

[0047] Example 3 Polymer production, press film molding, and dumbbell test specimen preparation were carried out in the same manner as in Example 1, except that the molar ratio of urea to 1,9-nonanediamine to 2-methyl-1,8-octanediamine in the polymer production was changed from 50.0 / 42.5 / 7.5 to 50.0 / 25.0 / 25.0. The number-average molecular weight of the obtained polymer was 4,900, the weight-average molecular weight was 15,000, and the molecular weight distribution was 3.1. The obtained measurement results and evaluation results are shown in Table 1.

[0048] Example 4 Polymer production, press film molding, and dumbbell test specimen preparation were carried out in the same manner as in Example 1, except that in the polymer production, urea, 1,9-nonanediamine, 1,10-decanediamine (manufactured by Tokyo Chemical Industry Co., Ltd.), and 2-methyl-1,8-octanediamine were used in a molar ratio of 50.0 / 0.5 / 42.0 / 7.5 instead of urea, 1,9-nonanediamine, and 2-methyl-1,8-octanediamine in a molar ratio of 50.0 / 42.5 / 7.5. The number-average molecular weight of the obtained polymer was 5,900, the weight-average molecular weight was 13,900, and the molecular weight distribution was 2.3. The obtained measurement and evaluation results are shown in Table 1.

[0049] Example 5 Polymer production, press film molding, and dumbbell test specimen preparation were carried out in the same manner as in Example 1, except that in the polymer production, urea, 1,9-nonanediamine, 1,12-dodecanediamine (manufactured by Tokyo Chemical Industry Co., Ltd.), and 2-methyl-1,8-octanediamine were used in a molar ratio of 50.0 / 0.5 / 42.0 / 7.5 instead of urea, 1,9-nonanediamine, and 2-methyl-1,8-octanediamine in a molar ratio of 50.0 / 42.5 / 7.5. The number-average molecular weight of the obtained polymer was 4,500, the weight-average molecular weight was 15,700, and the molecular weight distribution was 3.5. The obtained measurement and evaluation results are shown in Table 1.

[0050] Comparative Example 1 Polymer production, press film molding, and dumbbell test specimen preparation were carried out in the same manner as in Example 1, except that in the polymer production, urea, 1,10-decanediamine (manufactured by Tokyo Chemical Industry Co., Ltd.) and 2-methyl-1,5-pentanediamine (manufactured by Tokyo Chemical Industry Co., Ltd.) were used in a molar ratio of 50.0 / 42.5 / 7.5 instead of urea, 1,9-nonanediamine, and 2-methyl-1,8-octanediamine in a molar ratio of 50.0 / 42.5 / 7.5. The number average molecular weight of the obtained polymer was 5100, the weight average molecular weight was 12700, and the molecular weight distribution was 2.5. The obtained measurement and evaluation results are shown in Table 1.

[0051] Comparative Example 2 Polymer production, press film molding, and dumbbell test specimen preparation were carried out in the same manner as in Example 1, except that in the polymer production, urea, 1,10-decanediamine, and 1,3-pentanediamine (manufactured by Tokyo Chemical Industry Co., Ltd.) were used in a molar ratio of 50.0 / 42.5 / 7.5 instead of urea, 1,9-nonanediamine, and 2-methyl-1,8-octanediamine in a molar ratio of 50.0 / 42.5 / 7.5. The number average molecular weight of the obtained polymer was 7,000, the weight average molecular weight was 13,400, and the molecular weight distribution was 1.9. The obtained measurement and evaluation results are shown in Table 1.

[0052] Comparative Example 3 Polymer production, press film molding, and dumbbell test specimen preparation were carried out in the same manner as in Example 1, except that in the polymer production, urea and 1,10-decanediamine were used in a molar ratio of 50.0 / 50.0 instead of urea, 1,9-nonanediamine, and 2-methyl-1,8-octanediamine in a molar ratio of 50.0 / 42.5 / 7.5. The number-average molecular weight of the obtained polymer was 4,500, the weight-average molecular weight was 14,900, and the molecular weight distribution was 3.3. The obtained measurement results and evaluation results are shown in Table 1.

[0053] Comparative Example 4 Polymer production, press film molding, and dumbbell test specimen preparation were carried out in the same manner as in Example 1, except that in the polymer production, a mixture of urea and 2,2,4-trimethyl-1,6-hexanediamine / 2,4,4-trimethyl-1,6-hexanediamine (manufactured by Tokyo Chemical Industry Co., Ltd.) was used in a molar ratio of 50.0 / 50.0 instead of urea, 1,9-nonanediamine, and 2-methyl-1,8-octanediamine in a molar ratio of 50.0 / 42.5 / 7.5. The number average molecular weight of the obtained polymer was 4,200, the weight average molecular weight was 17,100, and the molecular weight distribution was 4.1. The obtained measurement and evaluation results are shown in Table 1.

[0054]

[0055] A comparison of Examples 1 to 5 with Comparative Examples 1 to 4 shows that a thermoplastic polyurea having aliphatic diamine units (A) having a linear aliphatic hydrocarbon group and aliphatic diamine units (B) having a methyl-branched aliphatic hydrocarbon group having a main chain of 7 to 12 carbon atoms has excellent chemical resistance and suppresses the occurrence of discoloration. A comparison of Example 5 with Example 1 shows that a decrease in the average carbon number of the linear aliphatic hydrocarbon group in the aliphatic diamine units (A) from 12 (Example 5) to 9 (Example 1) increases the melting point (196°C → 208°C) and improves chemical resistance (B → A).

[0056] A comparison between Example 3 and Example 1 shows that by changing the molar ratio (linear aliphatic diamine / branched aliphatic diamine) from 50 / 50 (Example 3) to 85 / 15 (Example 1), the melting point increases (178°C → 208°C) and the chemical resistance improves (B → A).

[0057] A comparison between Comparative Example 1 and Example 1 shows that chemical resistance is significantly improved (C → A) by changing the number of carbon atoms in the main chain of the methyl-branched aliphatic hydrocarbon group in the aliphatic diamine unit (B) from 5 (Comparative Example 1) to 8 (Example 1).

[0058] A comparison between Comparative Example 2 and Example 1 reveals that by changing the number of carbon atoms in the main chain of the aliphatic diamine unit (B) from 3 (Comparative Example 2) to 8 (Example 1), the melting point is significantly lowered (226°C → 208°C) and the occurrence of coloring is suppressed (C → A), and by changing the branch from an ethyl group (Comparative Example 2) to a methyl group (Example 1), the chemical resistance is improved (B → A).

[0059] According to the present invention, it is possible to provide a thermoplastic polyurea that has excellent chemical resistance and is capable of suppressing discoloration during melt molding, and a molded article containing the thermoplastic polyurea. The thermoplastic polyurea of ​​the present invention can be used, for example, in various substrates for electronic components, housings for electronic components, casings for electronic components, coverlays, wire coatings, laminate films, tubes for home appliances, industrial hydraulic belts, airless tires, tire inner liners, seal members, diaphragms, wire cables, bearing retainers, hair dryers, bobbin cases, mixer faucets, medical catheters, display cover films, wearable devices, etc.

Claims

1. A thermoplastic polyurea having an aliphatic diamine unit (A) having a linear aliphatic hydrocarbon group and an aliphatic diamine unit (B) having a methyl-branched aliphatic hydrocarbon group having 7 to 12 carbon atoms in the main chain.

2. The thermoplastic polyurea according to claim 1, wherein the molar ratio (A / B) of the aliphatic diamine units (A) to the aliphatic diamine units (B) is 99 / 1 to 30 / 70.

3. The thermoplastic polyurea according to claim 1 or 2, wherein the linear aliphatic hydrocarbon group has an average carbon number of 7 to 11.

4. The thermoplastic polyurea according to claim 1 or 2, wherein the bond between the aliphatic diamine unit (A) and the aliphatic diamine unit (B), the bond between the aliphatic diamine units (A) and the bond between the aliphatic diamine units (B) are urea bonds.

5. The thermoplastic polyurea according to claim 1 or 2, wherein the carbonyl group in the urea bond of the thermoplastic polyurea is derived from urea.

6. The thermoplastic polyurea according to claim 1 or 2, having a melting point of 220°C or less.

7. A molded article comprising the thermoplastic polyurea according to claim 1 or 2.

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