COPOLYMERIZED POLYAMIDE RESIN

Abstract: A copolymerized polyamide resin composed of 99 to 5 parts by weight of a polyamide component containing at least one kind of repeating units represented by the general formula (1) or (2): -NH(CH₂) n CO- (1) (wherein n represents an integer of 5 to 11) -NHXNHCOYCO- (2) (wherein X represents C m H 2m (where m is an integer of 6 to 12), an isophorone group, a phenylene group or a cyclohexylene group, and Y represents C₁H₂₁ (where 1 is an integer of 4 to 10), a phenylene group or a cyclohexylene group), and 1 to 95 parts by weight of a polyolefin component of average molecular weight 500 to 10,000 having carboxylic acid groups, amino groups or hydroxy groups at both its terminals. This resin has an extremely low absorbability.

Description: The present invention relates to a block copolymer polyamide resin having low water absorption. As is well known, polyamide resins find use in fiber and other broad application areas. However, they have the disadvantage that the dimensional stability of their moldings is poor end that their electrical and other properties are greatly affected by moisture, because they have inherently high water absorption due to their structure having the amide bond. The effect of moisture on the electrical properties is important, for example, in the field where polyamides are used as a heat-sensitive element or a temperature fuse for the heating element of electric blankets and electric carpets on account of their characteristics, namely that their impedance varies depending on the temperature and they have a sharp melting point inherent in crystalline polymers. Therefore, for such applications nylon 11 and nylon 12 are used which are comparatively low in water absorption among polyamide resins. Nevertheless, they are still susceptible to moisture and no satisfactory performance has been obtained. EP-A1-00 58 329 discloses block copolymers obtained from polyamides and dienpolymers having carboxylic acid, amino or hydroxyl end groups. FR-A-15 21 223 also discloses block copolymers containing polyamides and dienpolymers having amino end groups. Said block copolymers, however, have the tendency to form a gel. US-A-40 18 731 discloses a polyamide prepared by polymerisation, of polyamide forming monomers, e.g. caprolactam and a mixture of a dimerised fat acid (derivative) and a diolefin polymer, preferably conjugated diene homopolymer. It is the object of the present invention to provide a block copolymer polyamide resin improved in water absorption, which is an inherent disadvantage of polyamide, and improved in mechanical properties, moldability, and flexibility inherent in polyamide resin. Said object is achieved by a block copolymer polyamide resin having an average molecular weight of 5 000 to 500 000 which comprises copolymerized therein A) a polyamide polymeric component having at least one kind of repeating unit represented by the formula (1 ) or (2) -NH(CH₂) n CO- wherein n is an integer from 5 to 11; -NHXNHCOYCO- wherein X is C m H 2m with m being an integer from 6 to 12, an isophorone group, a phenylene group, or a cyclohexylene group; and Y is C l H₂ l with l being an integer from 4 to 10, a phenylene group, or a cyclohexylene group; and either B) a hydrogenated polyolefin component having a double bond hydrogenation ratio of at least 70% and an average molecular weight of 500 to 10 000, both terminals of said polyolefin being carboxylic acid groups or amino groups; wherein the weight ratio of A:B is from 99:1 to 5:95; or, in combination, C) a structural unit represented by the following formule (3) -CO-C m H 2m -CO- wherein m is an integer from 1 to 36; and D) a structural unit represented by the following formula (4) O-Z-O- wherein Z is a polybutadiene component having an average molecular weight of 500 to 10 000 with the double bonds being hydrogenated and the terminals connected to oxygen, with the proviso that a block copolymer comprising components (A) and (B) does not contain a dimerized fat acid or fat acid derivative having from 16 to 48 carbon atoms and having amide-forming functional groups at each terminal position in the molecular chain. The constituent units (A) and (C) are connected through the amide bond, the constituent units (A) and (D) are connected through the ester bond, and the constituent units (C) and (D) are connected through the ester bond. The constituent unit (D) accounts for 1 to 80 wt%; and the molar ratio of the constituent unit (C) to the constituent unit (D) is 1:1.2 to 1:0.8. The polyamide polymeric component constituting one part of the copolymer polyamide resin of this invention and having at least one kind of the repeating unti represented by the above formula (1) or (2) is composed of monomers such as caprolactam, lauryl lactam, 11-aminoundecanoic acid, and 12-aminododecanoic acid, which correspond to the formula (1), hexamethyleneadipamide, hexamethylenesebacamide, and hexamethylenedodecanamide, which correspond to formula (2), and diamine salts of cyclic dibasic acids such as terephthalic acid and cyclohexanedicarboxylic acid, and dibasic acid salt of diamines such as phenylenediamine, cyclohexanediamine, and isophoronediamine. The polyolefin component, with both terminals being carboxylic acid groups or amino groups, which constitutes the other part of the copolymer polyamid resin of this invention is obtained by radical polymerization of at least one kind of olefin monomer using a proper initiator, solvent, temperature, pressure, and other conditions so that the functional group which is the carboxylic acid group or amino group, is introduced into both terminals. The above-mentioned polyolefin component may also be obtained by polymerizing a monomer having two or more double bonds, with the terminals capped with functional groups selected from a carboxylic acid group or an amino acid group into a linear polymer and subsequently hydrogenating the linear polymer. The polybutadiene to be hydrogenated may contain any bonds, e.g., 1,2-bond, 1,4-trans bond, and 1,4-cis bond. Polybutadiene containing the 1,2-bond in a greater ratio is preferable from the standpoint of ease of hydrogenation. From an idealistic viewpoint, the polyolefin should definitely not have the above-mentioned functional group on the main chain and the terminals of the polyolefin should be fully capped with the functional group. However, it is inevitable that a small quantity of functional group is introduced into the main chain due to chain transfer in radical polymerization. It is also difficult to fully introduce the functional group into the terminals when stopping the living polymerization. Therefore, it is permissible to prepare the copolymer polyamide resin of this invention from the polyolefin component having 1.2 to 3.0 functional groups introduced in one molecule. A polyolefin having 1.5 to 2.2 functional groups per one molecule may be preferably used. It is technically difficult to completely hydrogenate a polymer composed of a monomer having two or more double bonds. Therefore, the copolymer polyamide resin of this invention is prepared from a polyolefin component having a hydrogenation ratio greater than 70%, preferably from a polyolefin component having a hydrogenation ratio greater than 90%. The polyolefin component in this invention is less effective to lower water absorption of the resulting polyamide resin, if the molecular weight is less than 500. The polyolefin component having a molecular weight greater than 10,000 does not provide the polyamide resin having favorable physical properties. Therefore, the polyolefin has an average molecular weight from 500 to 10,000. The copolymer polyamide resin of this invention should be composed of the two components at specific ratios. If the polyamide polymeric component is used in excess of 99 wt%, the resulting polyamide resin has almost the same physical properties as those of polyamides containing no polyolefin component. If the polyolefin component is used in excess of 95 wt%, the resulting polyamide resin has almost the same physical properties as those of polyolefins. Both cases are not preferable. The ratio of copolymerization should preferably be 95 to 30 parts by weight of the polyamide polymeric component and 5 to 70 parts by weight of the polyolefin component. The copolymer polyamide resin of this invention is polymerized in essentially the same manner as known polyamides in the case where the functional group of the polyolefin is carboxylic acid or amino group. The copolymer polyamide resin of this invention can be obtained by copolymerizing the monomer for the polyamide polymeric component and the polyolefin containing carboxylic acid groups or amino groups under the same polymerization conditions as used for polymerizing the monomer for the polyamide polymeric component, free of polyolefin component, constituting the copolymer. In the copolymerization step, diamine or dicarboxylic acid may be added according to the mol fraction of the polyolefin component in order to adjust the molecular weight of the copolymer. The diamine is exemplified by alkylenediamines such as hexamethylenediamine and dodecamethylenediamine; alicyclic diamines such as cyclohexanediamine; aromatic diamines such as phenylenediamine, or isophoronediamine. The dicarboxylic acid is exemplified by aliphatic dicarboxylic acids such as adipic acid, sebacic acid, and dodecanedioic acid; alicyclic carboxylic acids; and aromatic dicarboxylic acids such as phthalic acid. The copolymer polyamide resin of this invention is preferably produced by using a titanium catalyst. Preferable examples of such a catalyst include tetraalkyl titanates such as tetrabutyl titanate and tetramethyl titanate, and titanium-metal salts of oxalic acid such as titanium potassium oxalate. Other catalysts that can be used include tin compounds such as dibutyltin oxide and dibutyltin laurate, and lead compounds such as lead acetate. The copolymer polyamide resin of this invention may contain copolymerized therein a small quantity of diol components such as cyclohexane-dimethanol and 1,6-hexanediol, and polyfunctional compounds such as trimesic acid, glycerine, and pentaerythritol. The copolymer polyamide resin of this invention is a block copolymer composed of the polyamide polymeric component and the polyolefin component, and has a number-average molecular weight of 5,000 to 500,000. The copolymer polyamide resin of this invention may be incorporated, during polymerization or after polymerization and before molding, with stabilizers such as antioxidants, heat stabilizers, and light stabilizers, and other additives such as hydrolysis resistance improvers, colorants, flame retardants, reinforcements, fillers, molding aids, and plasticizers. The copolymer polyamide resin of this invention has low water absorption and undergoes little change in dimensions and physical properties due to water absorption, and has good heat resistance. Therefore, it is suitably used for making moldings by injection and extrusion. The copolymer is also used as hot-melt adhesive, solution adhesive, and coating material. The copolymer is flexible and superior in impact resistance when it contains more than 30 wt% of polyolefin. Such a copolymer may be used as an elastomer in the field where flexibility is required or as an impact resistance improver. The copolymer polyamide resin of this invention has low water absorption and its electrical properties, particularly impedance, depend little on moisture. It has a sharp melting point attributable to the polyamide block and has a characteristic a thermal fuse. Therefore, it can be advantageously used as a heat-sensitive element for electric blankets and electric carpets. The copolymer polyamide resin of this invention may be blended with polyamide resins such as nylon-11, -12, and -612 at a ratio of 99.9 to 30 parts by weight of nylon and 0.01 to 70 parts by weight of the copolymer polyamide resin of this invention. The invention is described with reference to the following examples. Example 1 In a 500-ml Erlenmeyer flask 76.40 g of 12-aminododecanoic acid, 1.57 g of hexamethylenediamine, and 28.92 g of hydrogenated polybutadiene terminated with carboxylic acids (prepared by 98% hydrogenated polybutadiene having more than 80% of 1,2-vinyl bond, and a concentration of 0.935 meq/g for the termainl carboxylic acid groups, were placed. The reactants were heated to 250°C under a nitrogen stream. On melting of 12-aminododecanoic acid, the condensation started, with bubbling of liberated water. After heating at 250°C for 3 hours, the reactants were cooled and the flask was broken to take out the resulting polymer which is light yellowish translucent and superior in impact resistance. The ratio of the nylon-12 component to the hydrogenated polybutadiene-hexamethylenediamine condensate component was 70/30 in this polymer. This polymer was dissolved in m-cresol to make a 0.5% solution. The relative viscosity at 25°C measured by an Ostwald viscometer was 1.43. The polymer was press-molded into a plate, and after immersion in water at 40°C for 10 days, water absorption measured by a DuPont moisture meter was 1.21 %. The melting point measured by DSC (Differential Scanning Calorimeter) was 172°C. The results of elemental analysis of this polymer are shown in Table 1. The IR spectrum gave absorptions characteristic of nylon-12 homopolymer and weak absorptions at 760 cm⁻¹ and 2960 cm⁻¹. Example 2 In a 300-ml Erlenmeyer flask 49.11 g of 12-aminododecanoic acid, 0.29 g of hexamethylenediamine, and 4.82 g of hydrogenated polybutadiene as used in Example 1 were placed. Polymerization was carried out in the same manner as in Example 1. On cooling, a polymer was obtained which is light yellowish translucent and superior in impact resistance. The ratio of the nylon-12 component to the hydrogenated polybutadiene-hexamethylenediamine condensate component was 90/10 in this polymer. This polymer was found to have a relative viscosity of 1.70, a water absorption of 1.49%, and melting point of 176°C when measured in the same manner as in Example 1. The results of elemental analysis of this polymer are shown in Table 2. Example 3 In a 500-ml separable flask 54.57 g of 12-aminododecanoic acid, 2.61 g of hexamethylenediamine, and 48.20 g of hydrogenated polybutadiene as used in Example 1 were placed. The reactants were heated at 220°C for 2 hours with stirring under a nitrogen stream. A polymer was obtained which is light yellowish transparent and flexible. The ratio of the nylon-12 component to the hydrogenated polybutadiene-hexamethylenediamine condensate component was 50/50 in this polymer. This polymer was found to have a relative viscosity of 1.30, a water absorption of 1.07%, and a melting point of 167°C when measured in the same manner as in Example 1. The results of elemental analysis of this polymer are shown in Table 3. The IR spectrum gave absorptions characteristic of nylon-12 homopolymer and weak absorptions at 760 cm⁻¹, 2860 cm⁻¹, and 2960 cm⁻¹. Example 4 In a 500-ml separable flask 32.74 g of 12-aminododecanoic acid, 3.66 g of hexamethylenediamine, and 67.48 g of hydrogenated polybutadiene as used in Example 1 were placed. Polymerization was carried out as in Example 3. A polymer was obtained which is light yellowish and very flexible. The ratio of the nylon-12 component to the hydrogenated polybutadiene-hexamethylenediamine condensate component was 30/70 in this polymer. This polymer was found to have a relative viscosity of 1.18, a water absorption of 0.95, and a melting point of 155°C when measured in the same manner as in Example 1. The results of elemental analysis of this polymer are shown in Table 4, The IR spectrum gave absorptions characteristic of nylon-12 homopolymer and weak absorptions at 760 cm⁻¹, 2860 cm⁻¹, and 2960 cm⁻¹. Example 5 In a 500-ml separable flask 76.40 g of 12-aminododecanoic acid, 5.80 g of 6-amino-caproic acid, 1.31 g of hexamethylenediamine, and 24.10 g of hydrogenated polybutadiene as used in Example 1 were placed. The reactants were heated at 240°C for 3 hours under a nitrogen stream. A polymer was obtained which is a light yellowish translucent. The ratio of nylon-12 component/nylon-6 component/hydrogenated polybutadienehexamethylenediamine condensate component was 70/5/25 in this polymer. This polymer was found to have a relative viscosity of 1.40, a water absorption of 1.57, and a melting point of 168°C when measured in the same manner as in Example 1. The results of elemental analysis of this polymer are shown in Table 5. Example 6 In a 500-ml separable flask 76.89 g of 11-aminoundecanoic acid, 1.57 g of hexamethylenediamine, and 28.92 g of hydrogenated polybutadiene as used in Example 1 were placed. Polymerization was carried out as in Example 5, A polymer was obtained which is a light yellowish translucent and superior in impact strength. The ratio of the nylon-11 component to the hydrogenated polybutadiene-hexamethylenediamine condensate component was 70/30 in this polymer. This polymer was found to have a relative viscosity of 1.46, a water absorption of 1.41, and a melting point of 186°C when measured in the same manner as in Example 1. The results of elemental analysis of this polymer are shown in Table 6. The IR spectrum gave absorptions characteristic of nylon-11 homopolymer and weak absorptions at 760 cm⁻¹ and 2960 cm⁻¹. Incidentally, nylon-11 homopolymer was found to have a melting point of 192°C and a water absorption of 1.9% when measured in the same manner as above. Example 7 In a 40-liter autoclave 1.4 kg of lauryl lactam, 578 g of hydrogenated polybutadiene as used in Example 1, 31.4 g of hexamethylenediamine, and 700 g of water were placed. The autoclave temperature was raised to 270°C over 3 hours. During the heating, the pressure was kept at 20 kg/cm². Reaction was carried out at 270°C and 20 kg/cm² for 5 hours. The pressure was released to 0 slowly over 4 hours, during which the temperature was decreased to 250°C. As soon as the pressure release was complete, nitrogen was fed into the autoclave, and 2 hours later, the polymer was extruded from the bottom of the autoclave and pelletized. The ratio of the nylon-12 component to the hydrogenated polybutadiene-hexamethylenediamine condensate component was 70/30 in this polymer. This polymer was found to have a relative viscosity of 1.57. Nylon-12 homopolymer having a relative viscosity of 1.90 and the copolymer of this example were blended at a weight ratio of 70/30 and 50/50, and the mixtures were mixed and extruded by a 30 mm extruder and pelletized. Test pieces with a notch for a Charpy impact test were prepared from the copolymer prepared in this example, the two blends, and nylon-12 homopolymer having a relative viscosity of 1.90. Charpy impact strength was measured for these test pieces at 23°C and 0°C. The results are shown in Table 7. It is to be noted from Table 7 that the copolymer prepared in this example is superior in impact resistance and is also effective to improve the impact strength of nylon-12 homopolymer when blended therewith. Comparative Example 1 After immersion in water at 40°C for 1 week, the molded sheet prepared in Example 1 was found to contain 0.502 wt% of water. The impedance measured for a sheet sample dried in vacuo at 70°C for 5 days and a sheet sample immersed in water at 40°C for 1 week was 3.0x10⁹ Ωcm and 2.4x10⁹ Ωcm at 50°C and 100 Hz, respectively. The difference was only 0.6x10⁹ Ωcm. On measurement of DSC at a heating rated of 10°C/min, the specimen exhibited a distinct melting behavior of crystalline polymer with a melting range from 153 to 176°C, a peak temperature of 170°C, and heat of fusion of 29.7 kJ/kg (7.1 cal/g). The fact that the copolymer is not very susceptible to moisture with respect to impedance and has a sharp melting point permits the copolymer to be used as a heat-sensitive element for electric blankets and electric carpets. Comparative Example 2 After immersion in water at 40°C for 1 week, a sheet sample of nylon-12 having a number-average molecular weight of 24,000 was found to contain 1.6 wt% of water. The impedance measured for a sheet sample dried in vacuo at 70°C for 5 days and a sheet sample immersed in water at 40°C for 1 week was 3.0x10⁹ Ωcm and 1.1x10⁹ Ωcm at 50°C and 100 Hz, respectively. The difference was a great as 1.9x10⁹ Ωcm. The sheet sample was found by DSC measurement to have a melting range from 164 to 184°C, a peak temperature of 178°C, and heat of fusion of 38.5 kJ/kg (9.2 cal/g).

Claims: 1. A block copolymer polyamide resin having an average molecular weight of 5000 to 500000 which comprises copolymerized therein (A) a polyamide polymeric component having at least one kind of repeating unit represented by the formula (1) or (2) -NH(CH₂) n CO- wherein n is an integer from 5 to 11; -NHXNHCOYCO- wherein X is C m H 2m with m being an integer from 6 to 12, an isophorone group, a phenylene group, or a cyclohexylene group; and Y is C ℓ H 2ℓ with ℓ being an integer from 4 to 10, a phenylene group, or a cyclohexylene group; and either (B) a hydrogenated polyolefin component having a double bond hydrogenation ratio of at least 70% and an average molecular weight of 500 to 10 000, both terminals of said polyolefin being carboxylic acid groups, or amino groups, wherein the weight ratio of A:B is from 99:1 to 5:95; or in combination, (C) a structural unit represented by the following formula (3) -CO-C m H 2m -CO- wherein m is an integer from 1 to 36; and (D) a structural unit represented by the following formula (4) -O-Z-O- wherein Z is a polybutadiene component having an average molecular weight of 500 to 10 000 with the double bonds being hydrogenated and the terminals connected to oxygen, with the proviso that a block copolymer comprising components (A) and (B) does not contain a dimerized fat acid or fat acid derivative having from 16 to 48 carbon atoms and having amide-forming functional groups at each terminal position in the molecular chain. 2. The polyamide resin of claim 1, wherein the ratio of the polyamide polymeric component to the polyolefin component is within the range of 95 to 30 parts by weight of the polyamide polymeric component to 5 to 70 ports by weight of the polyolefin component.

Inventors: ARITA, KOICHIRO, SUZUKI, HAJIME
Applicants: DAICEL CHEMICAL INDUSTRIES, LTD.
Application year: 1982
Main classification: C08G69
IPC codes: C08G81, C08G69