Resin composition, molded article, modifier for polyamide resin, and method for modifying polyamide resin

Abstract

This resin composition comprises a polyamide-based resin (A) and a modified ethylene / vinyl alcohol resin (B) grafted with an aliphatic polyester, the content of the modified ethylene / vinyl alcohol resin (B) being 1 part by weight or higher but lower than 50 parts by weight per 100 parts by weight of the total content of the polyamide-based resin (A) and the modified ethylene / vinyl alcohol resin (B). The resin composition has excellent moldability and gives molded objects excellent in terms of mechanical strength, particularly tensile rupture strain, while retaining intact transparency and solvent resistance.

Description

Technical Field

[0001] The present invention relates to a resin composition containing a modified ethylene-vinyl alcohol resin grafted with a polyamide resin and an aliphatic polyester, and more particularly to a resin composition that provides a molded article having excellent moldability, transparency, tensile fracture strain characteristics, and solvent resistance, the molded article, a modifier for a polyamide resin used therefor, and a method for modifying a polyamide resin.

Background Art

[0002] Conventionally, polyamide resins have been widely used as engineering plastics in various industrial fields including the automotive industry because of their excellent impact resistance, chemical resistance, abrasion resistance, etc.

[0003] Recently, the needs have been expanding for applications used in more severe environments, and various proposals have been made for improving the mechanical strength of molded articles made of polyamide resins.

[0004] For example, in order to obtain a molded article that exhibits excellent impact resistance even at extremely low temperatures of -40°C or lower, a technique of blending an olefin-based elastomer or the like with a polyamide resin has been proposed (see Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, as described above, when an olefin-based elastomer is blended with a polyamide-based resin to obtain a molded article, there is a problem that the transparency of the molded article decreases because the polyamide-based resin and the olefin-based elastomer are incompatible. In addition, since the solvent resistance decreases, there is also a problem that the applications are limited.

[0007] The present invention has been made in view of such circumstances, and provides a resin composition mainly composed of a polyamide-based resin, a molded article made of the resin composition, a modifier for a polyamide-based resin used for modifying the polyamide-based resin, and a method for modifying the polyamide-based resin, which can improve mechanical strength, particularly tensile fracture strain characteristics, without impairing the transparency and solvent resistance of the molded article.

Means for Solving the Problems

[0008] However, as a result of intensive research by the present inventors on a method for modifying a resin composition mainly composed of a polyamide-based resin to improve its mechanical strength without impairing the transparency and solvent resistance of the molded article, it has been found that when a specific modified ethylene-vinyl alcohol-based resin having compatibility with the polyamide-based resin is blended with the polyamide-based resin at a specific ratio, the moldability is excellent, the decrease in the transparency of the molded article is suppressed, and moreover, the tensile fracture strain characteristics and solvent resistance are improved.

[0009] That is, the present invention provides the following [1] to [9].

[0010] [1] A resin composition containing a polyamide-based resin (A) and a modified ethylene-vinyl alcohol-based resin (B) grafted with an aliphatic polyester, wherein when the total content of the polyamide-based resin (A) and the modified ethylene-vinyl alcohol-based resin (B) is 100 parts by weight, the content of the modified ethylene-vinyl alcohol-based resin (B) is 1 part by weight or more and less than 50 parts by weight.

[0011] [2] When the total content of the above polyamide resin (A) and the above modified ethylene-vinyl alcohol resin (B) is 100 parts by weight, the resin composition according to the above [1], characterized in that the content of the above modified ethylene-vinyl alcohol resin (B) is 1 to 45 parts by weight.

[0012] [3] The resin composition according to the above [1] or [2], characterized in that the modification rate of the above modified ethylene-vinyl alcohol resin (B) is 0.1 to 30 mol%.

[0013] [4] In the above modified ethylene-vinyl alcohol resin (B), the grafted aliphatic polyester is a ring-opening polymer of a lactone ring having 3 to 10 carbon atoms constituting the ring, and the resin composition according to any one of the above [1] to [3].

[0014] [5] The resin composition according to any one of the above [1] to [4], characterized in that the TOTAL haze measured in accordance with JIS K7105 using a haze meter (manufactured by Nippon Denshoku Co., Ltd., NDH2000) of a single-layer film with a thickness of 30 μm obtained using this resin composition is 2% or less.

[0015] [6] A molded article made of the resin composition according to any one of the above [1] to [5].

[0016] [7] The molded article according to the above [6], wherein the molded article is a sheet or a film.

[0017] [8] A modifier for polyamide resin comprising a modified ethylene-vinyl alcohol resin (B) grafted with an aliphatic polyester.

[0018] [9] A method for modifying a polyamide resin (A) by incorporating a modified ethylene-vinyl alcohol resin (B) grafted with an aliphatic polyester, wherein when the total content of the polyamide resin (A) and the modified ethylene-vinyl alcohol resin (B) is 100 parts by weight, the content of the modified ethylene-vinyl alcohol resin (B) is 1 part by weight or more and less than 50 parts by weight.

[0019] As described above, the resin composition of the present invention is a resin composition containing a polyamide resin (A) as a main component. For its modification, a specific modified ethylene-vinyl alcohol resin (B) having compatibility with the polyamide resin (A) is contained in a specific ratio with respect to the polyamide resin (A). Hereinafter, the "ethylene-vinyl alcohol resin" may be abbreviated as "EVOH", and the "modified EVOH grafted with an aliphatic polyester" may be abbreviated as "aliphatic polyester-modified EVOH" or "modified EVOH".

Advantages of the Invention

[0020] According to the above resin composition, since the polyamide resin (A) and the aliphatic polyester-modified EVOH (B) have compatibility, the amorphous part of the polyamide resin (A) and the modified EVOH (B) are compatible. As a result, the glass transition temperature (Tg) decreases, excellent tensile fracture strain characteristics are exhibited, and excellent moldability is provided. Therefore, the molded article obtained by the above resin composition has the advantage of maintaining excellent quality without impairing the original transparency and solvent resistance.

[0021] Further, according to the modifier for polyamide resin and the method for modifying polyamide resin of the present invention, a polyamide resin having excellent physical properties as described above can be provided only by incorporating the modifier into the polyamide resin.

Embodiments for Carrying Out the Invention

[0022] Hereinafter, embodiments for carrying out the present invention will be specifically described, but the present invention is not limited to these descriptions.

[0023] First, the resin composition of the present invention contains a polyamide-based resin (A) and an aliphatic polyester-modified EVOH (B), and these will be described in order separately in the following sections.

[0024] <Polyamide-based resin (A)> The polyamide resin (A) used in the present invention is not particularly limited. As general polyamide resins, for example, homopolymers such as polycapramide (nylon 6), poly-ω-aminoheptanoic acid (nylon 7), poly-ω-aminononanoic acid (nylon 9), polyundecanamide (nylon 11), and polylauryl lactam (nylon 12) can be mentioned. Also, as copolymer polyamide resins, there are polyethylene diamine adipamide (nylon 26), polytetramethylene adipamide (nylon 46), polyhexamethylene adipamide (nylon 66), polyhexamethylene sebacamide (nylon 610), polyhexamethylene dodecamide (nylon 612), polyoctamethylene adipamide (nylon 86), polydecamethylene adipamide (nylon 108), caprolactam / lauryl lactam copolymer (nylon 6 / 12), caprolactam / ω-aminononanoic acid copolymer (nylon 6 / 9), caprolactam / hexamethylenediammonium adipate copolymer (nylon 6 / 66), lauryl lactam / hexamethylenediammonium adipate copolymer (nylon 12 / 66), ethylenediamine adipamide / hexamethylenediammonium adipate copolymer (nylon 26 / 66), caprolactam / hexamethylenediammonium adipate / hexamethylenediammonium sebacate copolymer (nylon 66 / 610), ethyleneammonium adipate / hexamethylenediammonium adipate / hexamethylenediammonium sebacate copolymer (nylon 6 / 66 / 610), etc. of aliphatic polyamides, polyhexamethylene isophthalamide, polyhexamethylene terephthalamide, polymetaxylylene adipamide, hexamethylene isophthalamide / terephthalamide copolymer, poly-p-phenylene terephthalamide, poly-p-phenylene-3,4'-diphenyl ether terephthalamide, etc. of aromatic polyamides, amorphous polyamides, those obtained by modifying these polyamide resins with aromatic amines such as methylene benzylamine and metaxylylenediamine, and metaxylylenediammonium adipate, etc. Or these end-modified polyamide resins may be used, and end-modified polyamide resins are preferred.These polyamide resins can be used alone or in combination of two or more.

[0025] The melting point of the above polyamide resin (A) is preferably 160 to 270 °C, more preferably 180 to 250 °C, and particularly preferably 200 to 230 °C. When the melting point of such polyamide resin (A) is too low, the heat resistance of the resin composition tends to decrease. On the other hand, when the melting point of the polyamide resin (A) is too high, when the above polyamide resin (A) and the aliphatic polyester-modified EVOH (B) are blended in a twin-screw extruder, the die temperature is too high and the blended resin composition tends to undergo thermal degradation.

[0026] From the above viewpoints, preferred polyamide resins (A) include, for example, nylon 6 (melting point: about 220 °C) and nylon 6 / 66 (melting point: about 200 °C).

[0027] <Aliphatic polyester-modified EVOH (B)> Next, the aliphatic polyester-modified EVOH (B) used together with the above polyamide resin (A) will be described.

[0028] The above aliphatic polyester-modified EVOH (B) is a resin obtained by grafting an aliphatic polyester onto the hydroxyl group of EVOH.

[0029] The above EVOH is usually a resin obtained by saponifying an ethylene-vinyl ester copolymer, which is a copolymer of ethylene and a vinyl ester monomer, and is a water-insoluble thermoplastic resin.

[0030] As the polymerization method of the above ethylene and vinyl ester monomer, any known polymerization method can be used, for example, solution polymerization, suspension polymerization, emulsion polymerization, and generally solution polymerization using methanol as a solvent is used. And the saponification of the obtained ethylene-vinyl ester copolymer can also be carried out by a known method.

[0031] The EVOH produced in this way mainly consists of structural units derived from ethylene and vinyl alcohol structural units, and usually contains a small amount of vinyl ester structural units that remain without being saponified.

[0032] As the above vinyl ester monomer, vinyl acetate is typically used from the viewpoints of market availability and impurity treatment efficiency during production. Other vinyl ester monomers include, for example, vinyl formate, vinyl propionate, vinyl valerate, vinyl butyrate, isobutyl vinyl butyrate, vinyl pivalate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl versatate, etc. aliphatic vinyl esters, vinyl benzoate, etc. aromatic vinyl esters, etc. Usually, aliphatic vinyl esters having 3 to 20 carbon atoms, preferably 4 to 10 carbon atoms, particularly preferably 4 to 7 carbon atoms can be used. These can be used alone or in combination of two or more.

[0033] The content of the ethylene structural unit in the above EVOH can be controlled by the pressure of ethylene when copolymerizing the vinyl ester monomer and ethylene, and is usually 20 to 60 mol%, preferably 25 to 50 mol%, particularly preferably 30 to 45 mol%. When such content is too low, the melt moldability tends to decrease. Conversely, when it is too high, the gas barrier property tends to decrease. In addition, the content of such ethylene structural unit can be measured based on ISO14663.

[0034] Also, the saponification degree of the vinyl ester component in the above EVOH can be controlled by the amount, temperature, time, etc. of the saponification catalyst (usually an alkaline catalyst such as sodium hydroxide is used) when saponifying the ethylene-vinyl ester copolymer, and is usually 90 to 100 mol%, preferably 95 to 100 mol%, particularly preferably 99 to 100 mol%. When such saponification degree is too low, the gas barrier property, thermal stability, moisture resistance, etc. tend to decrease. The saponification degree of such EVOH can be measured based on JIS K6726 (however, EVOH is used as a solution uniformly dissolved in a water / methanol solvent).

[0035] In addition, the above EVOH may further contain structural units derived from the following comonomers within a range that does not inhibit the effects of the present invention (for example, 10 mol% or less of EVOH). Examples of the comonomer include olefins such as propylene, 1-butene, and isobutene; hydroxy group-containing α-olefins such as 3-butene-1-ol, 3-butene-1,2-diol, 4-penten-1-ol, and 5-hexene-1,2-diol, and derivatives thereof such as esterified products and acylated products; hydroxyalkyl vinylidenes such as 2-methylenepropane-1,3-diol and 3-methylenepentane-1,5-diol; hydroxyalkyl vinylidene diacetates such as 1,3-diacetoxy-2-methylenepropane, 1,3-dipropionyloxy-2-methylenepropane, and 1,3-dibutyryloxy-2-methylenepropane; unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, (anhydrous) phthalic acid, (anhydrous) maleic acid, and (anhydrous) itaconic acid, or salts or mono- or dialkyl esters thereof with an alkyl group having 1 to 18 carbon atoms; acrylamides such as acrylamide, N-alkylacrylamide with an alkyl group having 1 to 18 carbon atoms, N,N-dimethylacrylamide, 2-acrylamidopropanesulfonic acid or a salt thereof, and acrylamidopropyldimethylamine or an acid salt or quaternary salt thereof; methacrylamides such as methacrylamide, N-alkylmethacrylamide with an alkyl group having 1 to 18 carbon atoms, N,N-dimethylmethacrylamide, 2-methacrylamidopropanesulfonic acid or a salt thereof, and methacrylamidopropyldimethylamine or an acid salt or quaternary salt thereof; N-vinylamides such as N-vinylpyrrolidone, N-vinylformamide, and N-vinylacetamide; vinyl cyanides such as acrylonitrile and methacrylonitrile; vinyl ethers such as alkyl vinyl ether, hydroxyalkyl vinyl ether, and alkoxyalkyl vinyl ether with an alkyl group having 1 to 18 carbon atoms; vinyl halide compounds such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, and vinyl bromide; vinyl silanes such as trimethoxyvinylsilane; allyl halide compounds such as allyl acetate and allyl chloride; allyl alcohols such as allyl alcohol and dimethoxyallyl alcohol; and comonomers such as trimethyl-(3-acrylamido-3-dimethylpropyl)-ammonium chloride and acrylamide-2-methylpropanesulfonic acid.These can be used alone or in combination of two or more.

[0036] In particular, EVOH having a primary hydroxyl group in the side chain is preferable in that the secondary formability such as stretching treatment and vacuum / pressure-air forming becomes good. Among them, EVOH having a 1,2-diol structure in the side chain is more preferable.

[0037] Further, the EVOH used in the present invention may be “post-modified” such as urethanization, acetalization, cyanoethylation, oxyalkylation, acylation, etc.

[0038] Furthermore, the EVOH used in the present invention may be a mixture with other different EVOHs. Examples of such other EVOHs include those having different saponification degrees, different polymerization degrees, different copolymerization components, etc.

[0039] Next, a method for obtaining the aliphatic polyester-modified EVOH (B) used in the present invention using the above EVOH will be described. Examples of the modification method of the above EVOH include (1) a method of ring-opening polymerization of lactones in the presence of EVOH, and (2) a method of first subjecting an aliphatic polyester or lactones to ring-opening polymerization or condensation polymerization reaction to obtain a polyester having a carboxy group at the terminal, and then reacting the polyester having a carboxy group at the terminal with EVOH.

[0040] Among them, the method of ring-opening polymerization of lactones in the presence of EVOH is preferable because a resin in which an aliphatic polyester is grafted to EVOH can be easily obtained by a one-step reaction, and thus the number of man-hours is less and it is simpler and more preferable than the method of first generating an aliphatic polyester by ring-opening polymerization or condensation polymerization reaction and then reacting it with EVOH.

[0041] The above lactones are preferably lactones having 3 to 10 carbon atoms constituting the ring that forms an aliphatic polyester by ring-opening polymerization. When such lactones have no substituent, they are represented by the following general formula (1).

[0042] [Chemical formula]

[0043] In the above formula (1), n is an integer from 2 to 9, preferably n is 4 to 5. Also, any carbon atom of the alkylene chain -(CH 2 ) n - may have at least one substituent such as a lower alkyl group, a lower alkoxy group, a cycloalkyl group, a phenyl group, or an aralkyl group, each having about 1 to 8 carbon atoms.

[0044] Specific examples of such lactones include β-propiolactones, γ-butyrolactones, ε-caprolactones, δ-valerolactones, and the like.

[0045] Examples of the above β-propiolactones include β-propiolactone and dimethylpropionlactone.

[0046] Examples of the above γ-butyrolactones include butyrolactone, γ-valerolactone, γ-caprolactone, γ-caprylolactone, γ-laurolactone, γ-palmitolactone, γ-stearolactone, crotonolactone, α-angelicalactone, β-angelicalactone, and the like.

[0047] Examples of the above ε-caprolactones include monoalkyl-ε-caprolactones such as ε-caprolactone, monomethyl-ε-caprolactone, monoethyl-ε-caprolactone, monodecyl-ε-caprolactone, monopropyl-ε-caprolactone, and monodecyl-ε-caprolactone; dialkyl-ε-caprolactones in which two alkyl groups are each substituted on a carbon atom other than the ε-position; trialkyl-ε-caprolactones in which three alkyl groups are each substituted on a carbon atom other than the ε-position; alkoxy-ε-caprolactones such as ethoxy-ε-caprolactone; cycloalkyl-lactones such as cyclohexyl-ε-caprolactone; aralkyl-ε-caprolactones such as benzyl-ε-caprolactone; aryl-ε-caprolactones such as phenyl-ε-caprolactone, and the like.

[0048] Examples of the above δ-valerolactones include 5-valerolactone, 3-methyl-5-valerolactone, 3,3-dimethyl-5-valerolactone, 2-methyl-5-valerolactone, 3-ethyl-5-valerolactone, and the like.

[0049] These lactones can be used alone or in combination of two or more.

[0050] Among these, particularly, ε-caprolactones and δ-valerolactones are preferred, and ε-caprolactone is particularly preferred because it is inexpensive and easily available.

[0051] In the case of a reaction involving ring-opening polymerization, it is preferable to add a conventionally known ring-opening polymerization catalyst. Examples of the ring-opening polymerization catalyst include titanium-based compounds, tin-based compounds, and the like. Specifically, titanium alkoxides such as tetra-n-butoxytitanium, tetraisobutoxytitanium, and tetraisopropoxytitanium; tin alkoxides such as dibutyldibutoxysn; tin ester compounds such as dibutyltin diacetate, and the like. Among these, tetra-n-butoxytitanium is preferred because it is inexpensive and easily available.

[0052] In addition, the above reaction can also be carried out in a kneader such as a single-screw and twin-screw extruder, Banbury mixer, kneader, Brabender, etc. in a heat-melted state.

[0053] Also, the reaction time and temperature in the ring-opening polymerization are not particularly limited and can be appropriately selected. However, it is preferably carried out with stirring at 50 to 250 °C for 10 seconds to 24 hours, and more preferably carried out with stirring at 150 to 230 °C for 5 minutes to 10 hours. If the reaction time is too short compared to the lower limit value or the reaction temperature is too low compared to the lower limit value, the graft reaction rate decreases, and unreacted compounds tend to bleed out from the molded product, causing deterioration of the surface appearance. If the reaction time is too long compared to the upper limit value or the reaction temperature is too high compared to the upper limit value, crosslinking occurs between the modified EVOHs, and poor appearance of the molded product such as fish eyes tends to occur.

[0054] In the aliphatic polyester-modified EVOH (B) thus obtained, the content of the EVOH unit forming the backbone of the modified EVOH (B) is usually 40 to 99% by weight, preferably 45 to 95% by weight, particularly preferably 50 to 90% by weight, and the content of the aliphatic polyester unit grafted to this backbone is usually 1 to 60% by weight, preferably 5 to 55% by weight, particularly preferably 10 to 50% by weight. If the amount of EVOH units is too high, the mechanical strength, particularly the tensile fracture strain, does not improve, and the compatibility with the polyamide-based resin (A) decreases, so the effects of the present invention tend not to be obtained. On the other hand, if the amount of EVOH units is too low, the adhesiveness is strong, and the molded product tends to be easily blocked. The content of the EVOH unit and the content of the grafted aliphatic polyester unit in the aliphatic polyester-modified EVOH (B) can be 1 calculated from the results of 1H-NMR measurement.

[0055] In addition, the number average molecular weight (in terms of standard polystyrene measured by GPC) of the above-mentioned aliphatic polyester-modified EVOH (B) is usually 5,000 to 300,000, preferably 10,000 to 200,000, and particularly preferably 10,000 to 100,000. If the number average molecular weight of the above-mentioned modified EVOH (B) is too high, its melt viscosity will be too high, and the dispersibility in the polyamide-based resin (A) as the main component tends to decrease. On the other hand, if the number average molecular weight of the modified EVOH (B) is too low, its melt viscosity will be too low, and stable melt molding tends to be difficult. The number average molecular weight of the above-mentioned modified EVOH (B) can be calculated from the GPC measurement results.

[0056] And the modification rate (hereinafter also referred to as "graft modification rate" or simply "modification rate") of grafting the aliphatic polyester in the above-mentioned aliphatic polyester-modified EVOH (B) is usually 0.1 to 30 mol%, more preferably 1 to 25 mol%, and particularly preferably 5 to 20 mol%. If the above modification rate is too low, the mechanical strength as a modifier, especially the tensile fracture strain, is inferior, and the compatibility with the polyamide-based resin (A) decreases, so the effects of the present invention tend not to be obtained. On the other hand, if the above modification rate is too high, the adhesiveness is strong and blocking of the molded product tends to occur. The above modification rate can be 1 calculated from the 1H-NMR measurement results.

[0057] Furthermore, in the above-mentioned aliphatic polyester-modified EVOH (B), the average chain length of the aliphatic polyester unit grafted to its trunk is usually 1 to 15 mol, preferably 1 to 10 mol, and particularly preferably 1 to 8 mol. If the average chain length of the grafted aliphatic polyester unit is too long, the adhesiveness is strong and blocking of the molded product tends to occur. The average chain length of the above-mentioned aliphatic polyester unit can be 1 calculated from the 1H-NMR measurement results.

[0058] Specifically, under the following conditions 1By performing H-NMR measurement, the graft modification rate of the aliphatic polyester grafted onto the aliphatic polyester-modified EVOH (B) and the average chain length of the grafted aliphatic polyester can be calculated. (a) 1 H-NMR Measurement Conditions Internal standard substance: Tetramethylsilane Solvent: d6-DMSO Measured polymer concentration: 5 wt% (0.1 g of sample, 2 mL of solvent) Measurement temperature: 50 °C (323 K) Irradiation pulse: 45° pulse Pulse interval: 10 sec Number of integrations: 16 times (b) Assignment of resonance absorption peaks (I) 0.8 - 0.9 ppm: -CH at the end of the aliphatic polyester-modified EVOH 3 (II) 1.0 - 1.9 ppm: -CH in the main chain of the aliphatic polyester-modified EVOH 2 - and -CH adjacent to each other in the aliphatic polyester 2 - (III) 2.0 ppm: -CH of the remaining acetyl group in the aliphatic polyester-modified EVOH 3 (IV) 2.1 - 2.3 ppm: -CH adjacent to the carboxy group of the aliphatic polyester 2 - (V) 3.3 - 4.0 ppm: -CH adjacent to -OH of the aliphatic polyester-modified EVOH and -CH adjacent to -OH of the aliphatic polyester 2 - (VI) 4.0 - 4.7 ppm: -CH adjacent to -OH of the aliphatic polyester-modified EVOH and the aliphatic polyester, and -CH adjacent to the ester bond of the aliphatic polyester 2 - (c) Calculation of the graft modification rate and average chain length of the aliphatic polyester Using the integrated values of each resonance absorption peak in (I) to (VI) above, a system of simultaneous equations of the following formulas (i) to (vi) was established, and the amount of graft-modified groups C (mol) and the average chain length n (mol) of the aliphatic polyester were calculated from the solutions of the system of simultaneous equations. Furthermore, from formula (vii), the graft modification rate X (mol%) of the aliphatic polyester was calculated. Formula (i): 3×M = [Integrated value of peak (I)] Formula (ii): (2×M)+(2×A)+(4×E)+(2×O)+(6×n + 2)×C = [Integrated value of peak (II)] Formula (iii): 3×A = [Integrated value of peak (III)] Formula (vi): 2×n×C = [Integrated value of peak (IV)] Formula (v): O+(2×C)=[Integrated value of peak (V)] Formula (vi): O+(2×n - 1)×C = [Integrated value of peak (VI)] Formula (vii): X = C / (M + A + O + C + E)×100 Here, M, A, O, C, n, E, and X represent the following values. M: Amount of terminal methyl groups (mol) of aliphatic polyester-modified EVOH A: Amount of acetyl groups (mol) of aliphatic polyester-modified EVOH O: Amount of hydroxyl groups (mol) of aliphatic polyester-modified EVOH C: Amount of aliphatic polyester graft-modified groups (mol) of aliphatic polyester-modified EVOH n: Average chain length (mol) of aliphatic polyester E: Amount of ethylene groups (mol) of aliphatic polyester-modified EVOH X: Graft modification rate (mol%) of aliphatic polyester-modified EVOH

[0059] In addition, the glass transition temperature (Tg) of the aliphatic polyester-modified EVOH (B) used in the present invention is usually -50 to 60°C, preferably -30 to 45°C, and particularly preferably -10 to 35°C. If the glass transition temperature is too low, blocking of the molded product tends to occur easily. On the other hand, if the glass transition temperature is too high, the effects of the present invention tend not to be obtained. The above glass transition temperature can be measured using a differential scanning calorimeter.

[0060] Specifically, the glass transition temperature of the aliphatic polyester-modified EVOH (B) can be calculated by measuring using a differential scanning calorimeter under the following conditions. (a) Conditioning of the test piece: After melting at 230°C for 1 minute, the sample was cooled to -30°C at a cooling rate of 10°C / min. (b) Analysis of the glass transition temperature: The sample cooled in (a) was heated to 230°C at a heating rate of 10°C / min. (c) Calculation of the glass transition temperature: From the DSC curve obtained in (b), the midpoint temperature of the stepwise change portion of the glass transition was calculated as the glass transition temperature.

[0061] In addition, the MFR (melt flow rate) of the above aliphatic polyester-modified EVOH (B) is usually 0.5 to 100 g / 10 min, preferably 1 to 50 g / 10 min, and particularly preferably 3 to 35 g / 10 min. When such MFR is too large, the melt viscosity of the modified EVOH (B) is too low, and stable melt molding tends to be difficult. When such MFR is too small, the melt viscosity of the modified EVOH (B) becomes too high, and the dispersibility in the polyamide-based resin (A) tends to decrease. Such MFR is an index of the degree of polymerization of EVOH that forms the backbone of the modified EVOH (B), and can be adjusted by the amount of the polymerization initiator and the amount of the solvent when copolymerizing the monomers.

[0062] <Resin composition> Next, the resin composition of the present invention will be described. The resin composition of the present invention is a resin composition containing the polyamide-based resin (A) and the aliphatic polyester-modified EVOH (B).

[0063] When the total content of the polyamide-based resin (A) and the modified EVOH (B) is set to 100 parts by weight, the content ratio of the polyamide-based resin (A) and the aliphatic polyester-modified EVOH (B) is set such that the content of the modified EVOH (B) is 1 part by weight or more and less than 50 parts by weight.

[0064] That is, the lower limit of the content of the modified EVOH (B) is 1 part by weight, preferably 5 parts by weight or more, and more preferably 10 parts by weight or more. The upper limit of the content of the modified EVOH (B) is less than 50 parts by weight, preferably 45 parts by weight or less, more preferably 40 parts by weight or less, still more preferably 30 parts by weight or less, and particularly preferably 20 parts by weight or less. Among them, in particular, the content of the modified EVOH (B) is preferably 1 part by weight or more and 45 parts by weight or less, more preferably 1 part by weight or more and less than 40 parts by weight, and still more preferably 1 part by weight or more and less than 20 parts by weight.

[0065] That is, when the content of the modified EVOH (B) exceeds the above range, the balance of the compatible state of the two resins (A) and (B) is disrupted, and the transparency, solvent resistance, and molding processability of the resulting molded product tend to decrease. Moreover, the effect of improving the tensile fracture strain characteristics tends to be lost. On the other hand, when the content of the modified EVOH (B) is too small, the modification effect on the polyamide-based resin (A) tends to be lost.

[0066] In addition, the resin composition of the present invention may appropriately contain, as other components, a carboxylic acid-modified polyolefin resin (C), a hydrocarbon resin having a number average molecular weight of 100 to 3000 and a softening point of 60°C or higher and less than 170°C, an antioxidant, a lubricant, an antistatic agent, a colorant, an ultraviolet absorber, a plasticizer, a heat stabilizer, a light stabilizer, a surfactant, an antibacterial agent, a desiccant, an antiblocking agent, a flame retardant, a crosslinking agent, a curing agent, a foaming agent, a crystal nucleating agent, an anti-fogging agent, a biodegradable additive, a silane coupling agent, etc. within a range that does not inhibit the effects of the present invention (for example, 5% by weight or less of the entire resin composition).

[0067] <Preparation of Resin Composition> Next, a method for obtaining the resin composition of the present invention will be described. The resin composition of the present invention can be obtained by mixing the above polyamide resin (A), the modified EVOH (B), and optional components blended as required.

[0068] The above mixing method is not particularly limited, and each component can be directly used by dry blending. Generally, however, after mixing by a melt mixing method, a solution mixing method, etc., it is formed into a shape that is easy to handle, such as pellets, and prepared as a resin composition. From the viewpoint of productivity, the melt mixing method is preferred.

[0069] As the above melt mixing method, a method of melting and mixing after dry blending each component, or, for example, a known kneading device such as a kneader extruder, an extruder, a mixing roll, a Banbury mixer, a plastmill, etc. can be used. Usually, it is industrially preferable to use a single-screw or twin-screw extruder, and it is also preferable to provide a vent suction device, a gear pump device, a screen device, etc. as required.

[0070] The above melting and kneading temperature is usually in the range of 160 to 300°C, preferably 200 to 260°C, and particularly preferably 210 to 240°C, as the set temperature of the extruder and the die. If such temperature is too low, the resin tends to be in an unmelted state and the processing state tends to become unstable. If it is too high, the resin composition tends to be thermally deteriorated and the quality of the resulting molded product tends to decline.

[0071] <Molded article> Next, the molded article obtained by using the resin composition of the present invention will be described. The resin composition of the present invention is usually provided as a molded article having various shapes according to the purpose, such as a film, a sheet, a container, a fiber, a rod, a tube, etc. by melt molding or the like. Its uses include a wide variety of applications such as packaging materials, fibers, daily necessities, home appliance parts, automobile parts, medical members, civil engineering and construction materials.

[0072] As described above, in the molded article obtained by using the resin composition of the present invention, the amorphous part of the polyamide-based resin (A) which is the resin component and the modified EVOH (B) are compatible. As a result, the glass transition temperature (Tg) of the resin composition decreases and excellent tensile fracture strain characteristics are exhibited. Moreover, it has the advantage that the original transparency and solvent resistance are not impaired and excellent quality is maintained.

[0073] In addition, the TOTAL haze in the single-layer film with a thickness of 30 μm obtained by using the resin composition of the present invention is preferably 3.5% or less, more preferably 2% or less, and even more preferably 1.5% or less, which is a value measured in accordance with JIS K7105 using a haze meter (manufactured by Nippon Denshoku Co., Ltd., NDH2000). When the above TOTAL haze exceeds 3.5%, the transparency of the film tends to decrease. The above "TOTAL haze (%)" is expressed as a percentage of the diffused light transmittance of the test piece divided by the total light transmittance. The lower the value of the TOTAL haze, the better the film transparency.

[0074] Incidentally, the glass transition temperature of the resin composition of the present invention is preferably about 3 to 50 °C lower, particularly preferably about 8 to 20 °C lower, than the glass transition temperature of the polyamide resin (A) alone.

[0075] In addition, the molded article obtained by using the resin composition of the present invention can be used not only as a virgin product, but also by subjecting the pulverized product (such as when reusing the recovered product) made of the molded article to melt molding again. As the above melt molding method, an extrusion molding method (T-die extrusion, inflation extrusion, blow molding, melt spinning, profile extrusion, etc.) and an injection molding method are mainly adopted. The melt molding temperature is usually in the range of 160 to 300 °C, preferably 200 to 260 °C, particularly preferably 210 to 240 °C. If the above melt molding temperature is too low, the melt moldability tends to decrease due to insufficient fluidity, and if the above melt molding temperature is too high, the resin composition tends to be thermally deteriorated and appearance defects such as the generation of fish eyes and coloring tend to occur.

[0076] When forming a single-layer film or sheet using the resin composition of the present invention, the thickness thereof is usually 5 to 2000 μm, preferably 10 to 500 μm, more preferably 10 to 200 μm, although it depends on the application.

[0077] Furthermore, when forming the resin composition of the present invention into a film or sheet, it can be formed into various molded articles not only as a single molded article, but also as a multilayer structure having at least one layer made of the resin composition of the present invention.

[0078] Examples of the method for producing the above multilayer structure include a method of melt-extruding a thermoplastic resin onto a film or sheet containing the resin composition of the present invention, conversely, a method of melt-extruding the resin composition of the present invention onto a substrate such as a thermoplastic resin, a method of co-extruding the resin composition of the present invention and other thermoplastic resins, etc., and further, a method of dry laminating a film or sheet containing the resin composition of the present invention and a film or sheet of another substrate using a known adhesive such as an organotitanium compound, an isocyanate compound, a polyester compound, a polyurethane compound.

[0079] Among the above methods, the method of co-extruding the resin composition of the present invention with other thermoplastic resins is easy to manage the operation and is suitable. Examples of the thermoplastic resin and the like to be used in the case of co-extrusion include polyolefin resins, polyester resins, polyamide resins, copolyamide, polystyrene resins, polyvinyl chloride resins, polyvinylidene chloride, acrylic resins, vinyl ester resins, polyester elastomers, polyurethane elastomers, chlorinated polyethylene, chlorinated polypropylene, aromatic and aliphatic polyketones, aliphatic polyalcohols, and the like. Among them, polyolefin resins are preferably used in terms of having excellent mechanical properties and extrusion processability and being able to cope with a variety of moldings.

[0080] The above polyolefin resin is not particularly limited. For example, linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), ultra-low-density polyethylene (VLDPE), ethylene-vinyl acetate copolymer (EVA), and ionomer are preferable in terms of excellent flexural fatigue resistance, vibration fatigue resistance, etc. of the resulting laminated packaging material.

[0081] When obtaining a multilayer structure using the resin composition of the present invention, when the layer containing the resin composition of the present invention is a (a1, a2,...) and the layer made of other base materials, for example, a thermoplastic resin, is b (b1, b2,...), if it is in the form of a film, sheet, bottle, pipe, or tube, not only the two-layer structure of a / b, but also any combination such as b / a / b, a / b / a, a1 / a2 / b, a / b1 / b2, b2 / b1 / a / b1 / b2, b1 / b2 / a / b3 / b4, a1 / b1 / a2 / b2 is possible. Also, when making a fibrous or filamentous molded article, the resin composition of the present invention and other base materials can be combined and used in the same way, and any combination such as a bimetal type, core (a)-sheath (b) type, core (b)-sheath (a) type, or eccentric core-sheath type is possible for a and b.

[0082] In the above multilayer structure, an adhesive resin layer can be provided between each layer as needed. The resin used for the above adhesive resin layer varies depending on the type of resin used for the other layers in the above item b, so it cannot be generally stated. However, for example, a modified olefin-based polymer containing a carboxy group obtained by chemically bonding an unsaturated carboxylic acid or its anhydride to an olefin-based polymer by an addition reaction, a graft reaction, or the like can be mentioned.

[0083] Specifically, one or more mixtures selected from maleic anhydride graft-modified polyethylene, maleic anhydride graft-modified polypropylene, maleic anhydride graft-modified ethylene-propylene (block or random) copolymer, maleic anhydride graft-modified ethylene-ethyl acrylate copolymer, maleic anhydride graft-modified ethylene-vinyl acetate copolymer, etc. are preferably mentioned. At this time, the amount of the unsaturated carboxylic acid or its anhydride contained in the olefin-based polymer is preferably 0.001 to 3% by weight, more preferably 0.01 to 1% by weight, and particularly preferably 0.03 to 0.5% by weight. If the amount of modification in the above modified product is small, the adhesiveness tends to be insufficient. On the other hand, if it is large, a crosslinking reaction occurs and the moldability tends to deteriorate.

[0084] In addition, these adhesive resins can also be blended with the resin composition of the present invention, other EVOH, rubber and elastomer components such as polyisobutylene and ethylene-propylene rubber, and further the resin of the above b layer (the layer to be adhered). In particular, it is also possible to blend a polyolefin-based resin different from the polyolefin-based resin that is the matrix of the adhesive resin.

[0085] The thickness of each layer of the above multilayer structure cannot be generally stated as it depends on the layer composition, the type of the above b, the use, the shape of the molded article, the required physical properties, etc. Usually, the a layer is 5 to 2000 μm, further 10 to 500 μm, particularly 10 to 200 μm, the b layer is 5 to 5000 μm, further 30 to 1000 μm, and the adhesive resin layer is preferably selected from the range of about 5 to 400 μm, further 10 to 150 μm. Also, the thickness ratio of the a layer to the adhesive resin layer is usually such that the a layer is thicker. The ratio (thickness ratio) of the a layer / adhesive resin layer is usually 1 to 100, preferably 1 to 50, particularly preferably 1 to 10.

[0086] Also, in the above multilayer structure, the thickness ratio of the a layer to the b layer is such that, in a state where the thicknesses of the same type of layers in the multilayer structure are all added together, usually the b layer is thicker, and the ratio (thickness ratio) of the b layer / a layer is usually 1 to 100, preferably 3 to 20, particularly preferably 6 to 15. When the above a layer is too thin, mechanical properties such as rigidity and impact resistance tend to be insufficient, and the thickness control tends to become unstable. Conversely, when it is too thick, the flexural fatigue resistance tends to be inferior, and it tends to be uneconomical. Also, when the b layer is too thin, the rigidity tends to be insufficient, and conversely, when it is too thick, the flexural fatigue resistance tends to be inferior, and the weight tends to increase. On the other hand, when the adhesive resin layer is too thin, the interlayer adhesiveness tends to be insufficient, and the thickness control tends to become unstable. Conversely, when it is too thick, the weight tends to increase, and it tends to be uneconomical. Also, to each layer of the multilayer structure, for the purpose of improving the moldability and various physical properties, the above various additives, various modifiers other than the modified EVOH (B) used in the present invention, fillers, other resins, etc. can be added within a range that does not inhibit the effects of the present invention.

[0087] Furthermore, in order to improve the physical properties of the above multilayer structure, it is also preferable to perform a stretching treatment. The stretching treatment may be either uniaxial stretching or biaxial stretching. It is better in terms of physical properties to perform stretching at as high a magnification as possible. Molding products such as stretched films, stretched sheets, stretched containers, and stretched bottles that do not cause pinholes, cracks, uneven stretching, delamination, etc. during stretching can be obtained. As the stretching method, in addition to the roll stretching method, tenter stretching method, tubular stretching method, stretch blow method, etc., those with a high stretching ratio among deep drawing forming, vacuum-pressure air forming, etc. can also be adopted. In the case of biaxial stretching, either a simultaneous biaxial stretching method or a sequential biaxial stretching method can be adopted. The stretching temperature is usually selected from the range of 40 to 170°C, preferably about 60 to 160°C. If the stretching temperature is less than 40°C, the stretchability becomes poor, and if it exceeds 170°C, it tends to be difficult to maintain a stable stretching state.

[0088] And after the above stretching is completed, in order to impart dimensional stability to the stretched film, it is also preferable to perform heat setting. Heat setting can be carried out by well-known means. For example, the above stretched film is heat-treated at usually 80 to 180°C, preferably 100 to 165°C for usually about 2 to 600 seconds while maintaining a tension state. Also, when used for heat shrink packaging applications such as raw meat, processed meat, and cheese, after stretching, it is made into a product film without performing heat setting. After storing the above raw meat, processed meat, cheese, etc. in the film, heat treatment is usually performed at 50 to 130°C, preferably 70 to 120°C for usually about 2 to 300 seconds to heat-shrink the film and perform tight packaging.

[0089] The above multilayer structure can be used as it is for various shapes, such as films, sheets, tapes, bottles, pipes, filaments, extrusions with irregular cross-sections, etc. Also, when obtaining cup- or tray-shaped multilayer containers from multilayer sheets or multilayer films, a drawing forming method is adopted. Specifically, there are a vacuum forming method, a pressure air forming method, a vacuum-pressure air forming method, a plug assist type vacuum-pressure air forming method, etc. Further, when obtaining tube- or bottle-shaped multilayer containers from a multilayer parison (a hollow tubular preform before blowing), a blow molding method is adopted. Specifically, there are an extrusion blow molding method (double-headed type, mold moving type, parison shift type, rotary type, accumulator type, horizontal parison type, etc.), a cold parison type blow molding method, an injection blow molding method, a biaxial stretching blow molding method (extrusion type cold parison biaxial stretching blow molding method, injection type cold parison biaxial stretching blow molding method, injection molding in-line type biaxial stretching blow molding method, etc.), and so on. The obtained multilayer structure can be subjected to heat treatment, cooling treatment, rolling treatment, printing treatment, dry lamination treatment, solution or melt coating treatment, bag making processing, deep drawing processing, box processing, tube processing, split processing, etc., as necessary.

[0090] <Modifier for polyamide-based resin> Next, the modifier for the polyamide-based resin of the present invention will be described. The modifier for the polyamide-based resin of the present invention uses the aliphatic polyester-modified EVOH (B) itself used in the resin composition of the present invention as a modifier for the polyamide-based resin.

[0091] As already described, since the above modified EVOH (B) has compatibility with the polyamide-based resin (A), a resin composition obtained by blending this modified EVOH (B) as a modifier with the polyamide-based resin (A) has the amorphous part of the above polyamide-based resin (A) and the modified EVOH (B) being compatible. As a result, the glass transition temperature (Tg) decreases, excellent tensile fracture strain characteristics are exhibited, and excellent moldability is provided. Therefore, the molded product obtained from the above resin composition has the advantage that the original transparency and solvent resistance are not impaired and excellent quality is maintained.

[0092] Details of the modified EVOH (B) which is a modifier for the polyamide resin of the present invention have already been described as above, and the description thereof will be omitted.

[0093] Also, details of the polyamide resin to be modified by the modified EVOH (B) which is a modifier for the polyamide resin of the present invention are the same as those already described for the polyamide resin (A), and the description thereof will be omitted.

[0094] In addition, when the modified EVOH (B) which is a modifier for the polyamide resin of the present invention is blended with the polyamide resin (A) to modify its physical properties, the blending ratio is appropriately set according to the required degree of modification, the shape and use of the obtained molded product, etc. Usually, when the total content of the above polyamide resin (A) and the above modified EVOH (B) is 100 parts by weight, it is preferable to set the content of the above modified EVOH (B) to be 1 part by weight or more and less than 50 parts by weight.

[0095] More specifically, the lower limit of the content of the above modified EVOH (B) is preferably 1 part by weight, more preferably 5 parts by weight or more, and even more preferably 10 parts by weight or more. Also, the upper limit of the content of the above modified EVOH (B) is preferably less than 50 parts by weight, more preferably 45 parts by weight or less, even more preferably 40 parts by weight or less, particularly preferably 30 parts by weight or less, and even more preferably 20 parts by weight or less. And among them, in particular, it is preferable that the content of the above modified EVOH (B) is 1 part by weight or more and 45 parts by weight or less, more preferably 1 part by weight or more and less than 40 parts by weight, and even more preferably 1 part by weight or more and less than 20 parts by weight.

[0096] That is, when the content of the modified EVOH (B) exceeds the above range, the balance of the compatible state of the two types of resins (A) and (B) is disrupted, and the transparency, solvent resistance, and moldability of the resulting molded product tend to decrease. Moreover, the effect of improving the tensile fracture strain characteristics tends to be lost. On the other hand, when the content of the modified EVOH (B) is too small, the modifying effect on the polyamide-based resin (A) tends to be lost.

[0097] Moreover, the form of the modified EVOH (B) which is a modifier for polyamide-based resins of the present invention is not particularly limited, and for example, it may be in the form of powder, pellets, a solution, or a dispersion.

Examples

[0098] Hereinafter, the examples of the present invention will be specifically described together with comparative examples. However, the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

[0099] <Materials> First, the details of the materials used in the examples and comparative examples are shown below. · Polyamide-based resin (A1): Nylon 6 (manufactured by Mitsubishi Engineering Plastics Corporation, grade NOVAMID® 1022BLMJ) · Polyamide-based resin (A2): Nylon 6 (manufactured by DSM, grade NOVAMID® 1020) · Aliphatic polyester-modified EVOH (B1): Ethylene content 32 mol%, saponification degree 99.6%, graft modification rate 12.5 mol%, average chain length of aliphatic polyester 1.4 mol, glass transition temperature 18°C · Aliphatic polyester-modified EVOH (B2): Ethylene content 44 mol%, saponification degree 99.6%, graft modification rate 7.3 mol%, average chain length of aliphatic polyester 1.4 mol, glass transition temperature 20°C · Unmodified EVOH: Ethylene content 32 mol%, saponification degree 99.6%, glass transition temperature 61°C · Polyolefin-based elastomer: manufactured by Mitsui Chemicals, Toughmer MH7010, glass transition temperature -50°C · Polyester-based elastomer: manufactured by Mitsubishi Chemical Corporation, GQ430, glass transition temperature -50°C · Styrene-based elastomer: manufactured by Asahi Kasei Chemicals Corporation, Tough Tech M1913, glass transition temperature -45°C

[0100] <Description of evaluation items (evaluation methods and criteria)> Next, the details of the evaluation items for the example products and comparative example products are shown below.

[0101] (1) Tensile fracture strain Using pellets made of the resin compositions used in the examples and comparative examples, test pieces of ISO3167 Type A were produced with an injection molding machine and used as samples for measuring tensile fracture strain. Then, using a tensile testing machine (manufactured by Shimadzu Corporation, Autograph AGS-H), a tensile test was conducted under the following conditions, and the strain (%) at break was measured. · Test conditions: ISO527 · Temperature and humidity conditions: 23°C, 50%RH · Tensile speed: 50 mm / min

[0102] (2) Transparency (internal haze, TOTAL haze) Using pellets made of the resin compositions used in the examples and comparative examples, a single-layer film with a thickness of 30 μm was produced. Then, the transparency of this single-layer film was measured for TOTAL haze (%) in accordance with JIS K7105 using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., NDH2000). As described above, the "TOTAL haze (%)" is the percentage obtained by dividing the diffused light transmittance of the test piece by the total light transmittance, and the lower the value of TOTAL haze, the better the film transparency. In addition, in order to evaluate the haze inside the film, the internal haze (%) was measured using a sample with liquid paraffin applied to both sides of the film during measurement to remove the influence of surface irregularities of the film.

[0103] (3) Solvent resistance: toluene Using pellets made of the resin compositions used in the examples and comparative examples, test pieces with a length of 50 mm × width of 25 mm × thickness of 2 mm were produced using an injection molding machine. The obtained test pieces were immersed in toluene and allowed to stand still in a constant temperature chamber at 23°C and 50% RH, and the weight gain rate (g per 100 g of resin) after immersion for 1 week was evaluated.

[0104] (4) Glass transition temperature Samples (pellets) made of the resin compositions used in the examples and comparative examples were observed for their states by heating using a differential scanning calorimeter (Diamond DSC manufactured by Perkin Elmer), and the glass transition temperature was calculated. (a) Conditioning of test pieces: After heating to 250°C, the samples were cooled to -30°C at a cooling rate of 10°C / min. (b) Analysis of glass transition temperature: The samples cooled in (a) were heated to 250°C at a heating rate of 10°C / min. (c) Calculation of glass transition temperature: From the DSC curve obtained in (b), the midpoint temperature of the stepwise change part of the glass transition was calculated as the glass transition temperature.

[0105] (5) Molding processability (blocking) Samples (pellets) made of the resin compositions used in Examples 3 and 4 and Comparative Example 6 were heated at 150°C for 5 hours. After heating, it was visually observed whether blocking occurred in the pellets. When no blocking occurred, it was evaluated as "〇", and when blocking occurred, it was evaluated as "×". When blocking occurs, the fluidity of the pellets is lost, which causes clogging in the hopper tank, hopper, etc. during the molding process, resulting in a decrease in molding processability.

[0106] [Example 1] The polyamide resin (A1) and the aliphatic polyester-modified EVOH (B1) were introduced into the cylinder from the raw material supply port of a twin-screw kneading extruder (manufactured by Japan Steel Works, Ltd., TEX32) at the weight ratios shown in Table 1 below, conveyed to the kneading zone set at a temperature of 240°C, melt-blended, and the melt blend was extruded in a strand form from a die attached to the discharge port. The obtained strand-like extrudate was pelletized with a resin pelletizer to obtain a pellet-shaped resin composition.

[0107] [Example 2] A pellet-shaped resin composition was obtained in the same manner as in Example 1, except that the polyamide resin (A1) was changed to 80 parts by weight and the aliphatic polyester-modified EVOH (B1) was changed to 20 parts by weight.

[0108] [Examples 3 and 4, Comparative Examples 1 to 7] A pellet-shaped resin composition was obtained in the same manner as in Example 1, except that the types and weight ratios of the resins to be combined were changed as shown in Table 1 below.

[0109] Then, for the obtained Products of Examples 1 to 4 and Comparative Examples 1 to 7, measurements and evaluations were performed on the aforementioned evaluation items (tensile fracture strain, transparency [internal haze, TOTAL haze], solvent resistance, glass transition temperature, moldability [blocking]). These results are shown together in Table 1 below.

[0110]

Table 1

[0111] From the above results, it can be seen that Products of Examples 1 to 4 exhibit good characteristics in all evaluation items, while Products of Comparative Examples 1 to 7 receive poor evaluations in at least one of the items of tensile fracture strain, solvent resistance, transparency, glass transition temperature, and moldability, indicating that the modification effect on the polyamide resin (A) is insufficient.

[0112] In addition, in the above embodiments, specific forms of the present invention have been shown. However, the above embodiments are merely illustrative and should not be construed in a limiting manner. Various modifications obvious to those skilled in the art are all intended to be within the scope of the present invention.

Industrial Applicability

[0113] The present invention relates to a resin composition containing a polyamide resin (A) and an aliphatic polyester-modified EVOH (B), a molded article thereof, a modifier thereof, and a method for modifying a polyamide resin. The above resin composition is excellent in moldability, and the resulting molded article is excellent in transparency, tensile fracture strain characteristics, and solvent resistance, so these can be widely used.

Claims

1. A resin composition containing a polyamide resin (A) and a modified ethylene-vinyl alcohol resin (B) grafted with an aliphatic polyester, wherein when the total content of the polyamide resin (A) and the modified ethylene-vinyl alcohol resin (B) is 100 parts by weight, the content of the modified ethylene-vinyl alcohol resin (B) is 1 part by weight or more and less than 50 parts by weight, The resin composition is characterized in that the TOTAL haze measured in accordance with JIS K7105 using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., NDH2000) of a single-layer film with a thickness of 30 μm obtained using the resin composition is 2% or less.

2. The resin composition according to claim 1, wherein when the total content of the polyamide resin (A) and the modified ethylene-vinyl alcohol resin (B) is 100 parts by weight, the content of the modified ethylene-vinyl alcohol resin (B) is 1 to 45 parts by weight.

3. The resin composition according to claim 1 or 2, wherein the modification rate of the modified ethylene-vinyl alcohol resin (B) is 0.1 to 30 mol%.

4. The resin composition according to any one of claims 1 to 3, wherein in the modified ethylene-vinyl alcohol resin (B), the grafted aliphatic polyester is a ring-opening polymer of a lactone ring having 3 to 10 carbon atoms constituting the ring.

5. A molded article comprising the resin composition according to any one of claims 1 to 4.

6. The molded article according to claim 5, wherein the molded article is a sheet or a film.

7. A modifier for a polyamide resin used for applications other than tires, which comprises a modified ethylene-vinyl alcohol resin (B) grafted with an aliphatic polyester.

8. A method for modifying a polyamide resin (A) used for applications other than tires by incorporating a modified ethylene-vinyl alcohol resin (B) grafted with an aliphatic polyester into the polyamide resin (A), wherein when the total content of the polyamide resin (A) and the modified ethylene-vinyl alcohol resin (B) is 100 parts by weight, the content of the modified ethylene-vinyl alcohol resin (B) is 1 part by weight or more and less than 50 parts by weight.

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