THERMOPLASTIC RESIN COMPOSITION USED FOR MULTI-LAYERED MOLDING PRODUCT

Abstract: The invention is a thermoplastic resin composition having high tensile and impact strength and is suitable for use in containers requiring such properties such as fuel tanks. The composition comprises: (a) a polyolefin resin; (b) about 0.1 to about 5 wt.% of a polyamide, dispersed as particles of less than about 4 mu average size within said polyolefin resin, based upon the weight of the polyolefin resin; and (c) a modified polyolefin in an amount not less than about 0.2 times the weight of the polyamide. The thermoplastic resin composition may be laminated to nylon with a modified polyethylene adhesive layer between the thermoplastic resin and the nylon. The laminated product so produced is highly resistant to impacts and is suitable for use in fabricating fuel tanks and other impact-sensitive containers.

Description: -1- THERMOPLASTIC RESIN COMPOSITION USED FOR MULTI-LAYERED MOLDING PRODUCT 1. Field of the Invention 5 The present invention concerns a thermoplastic resin composition used for multi-layered molding products and, more particularly, relates to a thermoplastic resin composition suitable for use as a polyolefin layer in multi-layered highly impact 10 resistant molding products comprising a polyamide layer and a polyolefin layer. 2. Description of the Related Art Since polyolefin resins are inexpensive and !5 have high strength, they are generally suitable for use in the production of various kinds of containers. Polyolefin resins, however, suffer the disadvantage that they lack a high resistance to gas permeability. Consequently, they are not suitable for use as fuel tanks, such as gasoline tanks. There have been various attempts to blend polyamide resins having excellent gas-barrier properties, such as nylon, with polyolefin resins to form thermoplastic resin compositions which are excellent both in mechanical strength and gas barrier properties. See, for instance, Japanese Patent Laid-Open No. 54-123158, 59-232135, 62- 158739, 62-241938 and 62-242941. Further, it has been proposed to produce multi-layered molding products by laminating a polyamide layer to a polyolefin layer, rather than blending these two components, to obtain enhanced gas barrier properties. See Japanese Patent Laid-Open No. 54- 113678, 55-91634, 55-121017 and Japanese Patent Publication No. 60-14695. In these molding products, since the adhesion between the polyolefin layer and the polyamide layer is generally low, a modified, plastic layer, such as a polyolefin resin modified with an unsaturated carboxylic acid, is placed between the layers to act as an adhesive. It has also been suggested that one should recover the flash formed upon molding of multi- layered molding products and mix these with polyolefin for reuse. Japanese Patent Laid-Open No. 54-113678 and 55-91634. However, when the flash of the multi-layered molding products is blended with the polyolefin, one does not always obtain thermoplastic resin compositions that have acceptable adhesion strength and impact resistance. It is speculated that this is attributable to the poor compatibility between the polyolefin and the polyamide. Since impact resistance is particularly important in fuel tanks and other impact sensitive applications, a reduction in impact strength greatly impairs the commercial value of a product for such uses. Further, although the impact resistance can be maintained if flash is not used in production, this increases material costs and is therefore undesirable. Accordingly, it is an object of the present invention to provide a thermoplastic resin composition of excellent impact resistance. In particular, it is an objective to provide a thermoplastic resin composition suitable for use as a polyolefin layer in a multi-layered molding product comprising a polyamide layer and a polyolefin layer that has excellent impact resistance. Summary of the Invention The loss of impact strength when polyamide is blended into polyolefin is due to a "peeling phenomenon" at the polyolefin-polyamide interface. The inventors have found that the peeling phenomenon can be suppressed thereby improving the impact resistance of the resin composition. This is accomplished by adding an appropriate amount of a modified polyolefin and a polyamide to the polyolefin and insuring that the size of the dispersed particles or grains of polyamide in the resin composition is less than a predetermined size. The invention thermoplastic resin composition useful for producing multi-layered molding products comprises: (a) about 0.1 to about 5 wt.% of a polyamide based on the weight of the resin composition, (b) a polyolefin modified with an unsaturated carboxylic acid or its derivative in an amount not less than about l/5th of the blending amount of the polyamide, and (c) a balance substantially of a polyolefin resin and optimally additives for specific properties. The polyamide is dispersed in the thermoplastic resin composition, in a granular state, with an average grain size of not greater than about 4 microns. Brief Description of the Drawing Fig. 1 is a cross sectional view illustrating one embodiment of the layer structure for a multi- layered molding product prepared by using the resin composition according to the present invention. Detailed Description of the Preferred Embodiments The invention highly impact resistant thermoplastic resin composition comprises a polyolefin resin having dispersed therein fine particles of a polyamide and including a modified polyolefin as a compatibilizing agent. The polyamides useful in the present invention include those polyamide resins prepared from aliphatic, cycloaliphatic or aromatic diamines such as hexamethylene diamine, decamethylene dia ine, dodecamethylene diamine, 2,2,4- or 2,4,4- trimethylenehexamethylene diamine, 1,3- or 1,4- bis(aminomethyl)cyclohexane, bis(p- aminocyclohexylmethane) , m- or p-xylene diamine and aliphatic, cycloaliphatic or aromatic dicarboxylic acids such as adipic acid, suberic acid, sebacic acid, cyclohexane diacarboxylic acid, terephthalic acid or isophthalic acid; polyamide resins prepared from aminocarboxylic acid such as 6-aminocaproic acid, 11-aminoundecanic acid or 12-aminododecanic acid; polyamide resins prepared from lactams such as e-caprolactams or ω-dodecalactam; copolymerized polyamide resins comprising the above-mentioned ingredients or mixtures of such polyamide resins. Specific polyamides include nylon-6, nylon-66, nylon-11, nylon-12 and copolymers thereof. Furthermore, copolymers comprising more than 50% by weight y of such a nylon resin and resins other than those described above may also be used. The molecular weight of the polyamide is, preferably, within a range from 3,000 to 200,000 and more preferably within a range from 10,000 to 100,000. It is further preferred, for improving impact resistance, to incorporate from about 0.5 to 40 wt.% of a plasticizer such as e-caprolactam, N- butylbenzene sulfonamide or octyl p-oxybenzoate and the like in the polyamide. More preferably, the plasticizer is present in an amount from about 3-25 wt.%. The polyolefin used in the present invention may be a homopolymer of α-olefin such as ethylene, propylene, butene-1, hexene-1 or 4-methylpentene-l; a copolymer of ethylene with propylene or another α- olefin, or a copolymer of ethylene with two or more of such α-olefins. Polyethylene, such as low density polyethylene, linear low density polyethylene, medium density polyethylene or high density polyethylene, as well as polypropylene are preferred. Further, a copolymer of polyethylene or polypropylene with a polymer other than those described above and containing more than 75 wt.% of polyethylene or polypropylene may be used. The useful polypropylene is not restricted to polypropylene homopolymers but include random or block copolymers with other α-olefins containing more than 50 mol %, preferably more than 80 mol % polypropylene. Suitable co onomers for propylene include ethylene or like other α-olefins, ethylene being particularly preferred. Accordingly, the term "polypropylene" used in the specification and claims should be construed as including polypropylene copolymers. When polyethylene is used as the polyolefin, it is preferred that the high load melt-index (HLMI, at 190oC under 21.6 kg of load) be greater than 0.1 g/10 min and the melt-index (MI, at 190°C under 2.16 kg of load) be less than 100 g/10 min. More preferably, the high load melt-index should be greater than 1 g/10 min and the melt-index less than 50 g/10 min. In the case of polypropylene, the melt flow rate (MFR, at 230°C under 2.16 kg of load) is within a range from 0.01 to 150 g/10 min, preferably from 0.1 to 75 g/10 min. By using polyethylene or polypropylene having a melt flow property within these ranges, a composition may readily be kneaded or blended to disperse polyamide particles homogeneously. The modified polyolefin used in the present invention is a polyolefin modified with an unsaturated carboxylic acid or its anhydride. Examples of the unsaturated carboxylic acid or its anhydride, include for example monocarboxylic acids such as acrylic acid or methacrylic acid, dicarboxylic acids such as maleic acid, fumaric acid or itaconic acid, dicarboxylic acid anhydrides such as maleic acid anhydride, itaconic acid anhydride or himic acid anhydride. Dicarboxylic acids and their derivatives are particularly preferred. Specifically, a modified polyolefin with maleic acid anhydride or himic acid anhydride are particularly preferre . The unsaturated carboxylic acids or their derivatives in the modified polyolefin are preferably present in the invention composition in the range from 0.005 - 5 wt.%. When maleic acid anhydride is used, its preferred range is from 0.01 - 3 wt.%, more preferably, 0.1 - 1 wt.%. When himic acid anhydride is used the preferred range is from 0.015 - 4 wt.%, more preferably, from 0.15 to 1.5 wt.%. If the degree of modification with maleic acid anhydride or himic acid anhydride is less than the above-specified lower limits, then there is not a significant or effective improvement in compatibility between the polyamide and the polyolefin. On the other hand, if the amount exceeds the above-mentioned upper limits, compatibility is reduced. It is preferred that the molar ratio of the terminal amines of the polyamide to the carboxylic acid groups in the modified polyolefin be greater than 0.1, for improved impact resistance. The modified polyolefin can be prepared by either a solution method or a melt-kneading method. In the case of the melt-kneading or melt-blending method, a polyolefin, a modifying unsaturated carboxylic acid (or acid anhydride) and a catalyst are charged to an extruder, double-screw kneader, etc. and melt blended while heating at a temperature of about 150 - 250°C. In the case of the solution method, the starting materials are dissolved in an organic solvent, such as xylene, and preparation is conducted while stirring at a temperature from about 80 to about 140°C. In either of these cases, a radical polymerization catalyst may be used, for example peroxides, such as benzoyl peroxide, lauroyl peroxide, ditertiary butyl peroxide, acetyl peroxide, tertiary butyl peroxybenzoic acid, dicumyl peroxide, peroxybenzoic acid, peroxyacetic acid, tertiary butyl peroxypivalate, or 2,5-dimethyl-2,5 ditertiary butyl peroxy hexine; or diazo compounds such as azobisisobutyronitrile are preferred. The catalyst is added in amounts from about 1 to about 100 parts by weight, based upon 100 parts by weight of the modifying unsaturated carboxylic acid or its anhydride. As the size of the polyamide particles dispersed in the resin composition is reduced, the impact resistance is further improved. The more preferred grain size of the dispersed polyamide is less than two microns on average. In the invention thermoplastic resin composition, the content of the polyamide is from 0.1 to 5 wt.%, preferably from 0.1 to 3 wt.% based upon the resin content. The content of the modified polyolefin is not less than 0.2 times, preferably 1 - 4 times the polyamide content. The balance substantially comprises a polyolefin and optional additives and fillers. The average grain size of the dispersed polyamide particles in the resin composition may be reduced to less than 4 microns by blending or kneading the composition for a sufficient length of time under melt conditions. If the polyamide is less than 0.1 wt.%, the composition is ineffective for modifying the polyolefin and improving the impact resistance. On the other hand, if the polyamide content exceeds 5% by weight, the composition develops brittleness and no improvement in impact resistance is obtained. Further, if the content of the modified polyolefin is not more than 0.2 times the polyamide content, the compatibility between the polyolefin and the polyamide is not improved. Thus, the peeling phenomenon between the polyolefin and the polyamide is not suppressed. The invention thermoplastic resin composition may also include inorganic fillers such as carbon, etc. in order to improve mechanical strength, heat resistance, etc. When such fillers are added, it is preferred that the blending ratio of the thermoplastic resin composition be more than 50 volume percent at 23°C. If additives such as organic fillers or carbon black comprise more than 50 percent by volume, not only is the moldability of the composition reduced thereby making it difficult to prepare a molding product, but the mechanical strength is also reduced. Other additives may also be included in the invention composition, for example, heat stabilizers, light stabilizers, flame retardants, plasticizers, antistatic agents, releasing agents, foaming agents and nucleating agents. The invention composition may be produced by kneading or blending in a molten state while heating by using an extruder, such as a single or double screw extruder. Further, each of the above ingredients may be premixed in a Henschel mixer, or the like, and the mixture may then be melt-kneaded in an extruder. Further, upon melt kneading of the composition, if there is a great difference in the melt viscosity between the polyolefin and the modified polyolefin, and the polyamide, the dispersion may be improved by pre-kneading the polyamide and the modified polyolefin under melt conditions and thereafter kneading them together under melt conditions with the polyolefin. A multi-layered molding product having a layer structure as shown in Fig. 1 can be prepared using the invention composition. The multi-layered molding product comprises resin layers 1,1 composed of a composition according to the present invention; a polyamide resin layer 2 and modified polyolefin layers 3,3 for bonding the layers. When a modified polyolefin, for example, is incorporated into the resin layers 1,1 the adhesion strength between each of the layers is increased thereby increasing the mechanical strength of the multi-layered product. When the polyamide layer 2 is used as the inner layer 2, the multi-layered molding product also has excellent water proof properties. The multi-layered molding product can be prepared for example, by a blow-molding process, in which flash formed in the production can be recovered and kneaded with the resin for forming the resin layers 1,1. The flash contains polyolefin, modified polyolefin and polyamide resin. Since the flash has the-*same composition as the invention composition,, it can be kneaded into the mixture without reducing compatibility. The composition ratio of the polyolefin, the modified polyolefin and the polyξimide resin in the flash varies depending upon the thickness of each of the layers of the multi-layered molding product. Thus, if resin is added to the blend composition taking the composition of the flash into account, then flash can be readily reused. In summary, although compatibility between polyamides and polyolefins is poor, they can be compatibilized using a polyolefin modified with an unsaturated carboxylic acid or its derivatives. In particular, the occurrence of a peeling phenomenon at the interface of the polyolefin and polyamide can be prevented by adding a modified polyolefin and reducing the average grain size of the particles of the polyamide dispersed in the polyolefin to less than about 4 microns. Carboxylic acid groups in the modified polyolefin react with terminal amines in the polyamide resin to form a polyamide-modified polyolefin copolymer uniformly distributed within the thermoplastic resin. The following Examples are intended to illustrate the invention as described above and claimed hereafter and do not limit the scope of the invention as described above and claimed herebelow. Examples 1 - 6 Nylon-6 having a number average molecular weight of 30,000 and containing 8% by weight of e- caprolactam as a plasticizer, was dry blended in a high speed mixer with a modified polyethylene (containing 0.4 wt.% of maleic acid anhydride and having a 0.5 g/10 min melt index) and a polyethylene (having a density of 0.955 g/cm 3 and having a melt index (MI) of 0.5 g/10 min) in the blending ratios shown in Table I. These blends were then charged to a single-screw extruder and kneaded at 240°C to obtain pellets of the composition. The resultant pellets were dried and test specimens were prepared by injection molding. The cylinder temperature in the injection molding was set to 240°C. Tensile impact tests were conducted at 23°C and -40°C according to ASTM D1822-S. The results are shown in Table I. Examples 7 - 14 Blends were prepared wherein the Nylon-6 did not include the plasticizer, e-caprolactam. Blend compositions are shown in Table I. Test specimens were prepared and tested as detailed above for Examples 1-6. Comparative Examples 1 - 4 For comparison, blends were prepared using polyamides shown in Table II and the same modified polyethylene and the polyethylene as the blends of Example 1. The blending ratios are shown in Table II. Test specimens were prepared and tested using the procedures of Examples 1-6. The results are shown in Table II. Examples 15 - 20 Blends shown in Table III were prepared with Nylon-6 (having a number average molecular weight of 30,000 and containing 8% by weight of e- caprolactam) , a modified polyolefin (0.4 wt.% of addition rate of maleic acid anhydride and having a melt flow rate (MFR) of 50 g/10 min, at 230°C under 2.16 kg of load), and a propylene homopolymer (having MFR of 9 g/10 min) using the same procedures as those in Example 1. Test specimens were prepared using the same procedures of Example 1. An Izod impact test was conducted at 23°C and -20°C according to the JIS K-7110 method. The results are shown in Table III. Examples 21 - 28 Blends 21-28 were prepared with the nylons shown in Table III and the same modified polypropylene and the polypropylene as those of Example 15. Test specimens were prepared by the method of Example 15 and Izod impact tests were conducted. The results are shown in Table III. Comparative Examples 5 - 8 For comparison, comparable blends 5-8 shown in Table IV were prepared using Nylon-6 as the polyamide and the same modified polypropylene and the polypropylene as in Example 15. Test specimens were prepared by the same procedures as those of Example 15 and an Izod impact test was conducted. The results are shown in Table IV. The test specimens produced by the invention have higher values for both tensile impact and strength and Izod strength. Example 29 70 liter volume fuel tanks comprising five layers of three components as shown in Fig. 1 were molded using the composition of Example 2 as the thermoplastic resin layer. The composition of Example 2 was used for the innermost and the outermost layers (layers 1,1 in Fig. 1), Nylon-6 was used for the intermediate layer (layer 2 in Fig. 1) and the modified polyethylene was used for the adhesion layer (layers 3,3 in Fig. 1). The outermost layer and the innermost layers comprising the composition of Example 2 were 1800 microns and 1840 microns thick, respectively. The intermediate layer comprising Nylon-6 was 120 microns thick and the adhesion layer, comprising the modified polyethylene, was 120 microns thick. A drop impact test was conducted in the following manner. Water was charged into 10 fuel tanks to the same weight as that of the fuel, that would be required to fill the tanks. Each filled tank was then dropped from heights (6, 8, 10 and 12 meters) to determine the height from which the tank failed. The results are shown in Table V. Example 30 70 liter volume fuel tanks, each comprising five layers composed of three ingredients, and having the same layered structure as that of Example 29, were also molded by the same procedures as those in Example 29 except that flash was incorporated into the thermoplastic resin layer. A blend comprising 100 parts by weight of recovered flash upon molding the fuel tanks in Example 29 and 100 parts by weight of the composition in Example 2 (average grain size of polyamide of 0.5 microns) was prepared and used for the innermost layer and the outermost layers of the fuel tank. A drop impact test was conducted by the same procedures as those in Example 29. The results are shown in Table V. Comparative Example 9 70 liter volume fuel tanks comprising five layers and composed of three ingredients having the same layer structure as that in Example 29 were molded in the same manner except that a high density polyethylene (density: 0.955, melt index: 0.5 g/10 min) was used for the innermost and the outermost layers of the fuel tanks. A drop impact test was conducted in the same procedures as those in Example 29. The results are shown in Table V. TftPMS I Average grain size, microns 0.5 0.5 0.5 The polyamide is a nylon. For blende 1-6, 8 wt.% ε-caprolactam was added to the polyamide. Blende 1-6 contained Nylon-6, blend 11 contained Nylon-66, blend 12 contained Nylon-11, blend 13 contained Nylon-12 and blend 14 contained a copolymer of Nylon-6 and 12, 7125U of Ube Kosan Co. 2 0.4 wt.% maleic acid anhydride addition rate, MI 0.4 g/10 min. 3 0.955 g/cc, MI 0.5 g/10 min. 4 ASTM D 1822S method. TABLE II Component Polyamide ,1' 8 Modified Polyethylene 1 Polyethylene 100 91 Tenβile impact strength, θ 23 * C 310 198 Kg • cm/cm 2 @ -40'C 195 118 λverage grain size, microns I I e Blends 1 and 2 used Nylon-6 with 8 wt.% e-caprolactam while blend 4 contained no -.-caprolactam. TABLE III Components Blends 15 J_έ l2 1fi lS 2fi 21 22 22 21 2£ 2_6 22 2fi Polyamide 1 Modified Polyethylene 2 Polyethylene homopolymer 3 Izod Impact Strength* (kg»cra/cm 2 ) § 23 * C @ -40'C Average grain size, microns 0.5 0.5 0.5 Blends 15-26 used Nylon-6, blend 25 used Nylon-66, blend 26 used Nylon-11, blend 27 used Nylon-12 and blend 28 used a random copolymer of Nylons 6 and 12, 7125U of Ube Kosan Co. 2 0.4 wt.% addition rate of maleic acid anhydride, MFR 50 g/10 min. 3 MFR 9 g/10 min. According to JIS K 7110 (with notch). TABLE IV Component 8 Polyamide 1 8 Modified Polyethylene 2 1 Propylene homopolymer 3 100 91 Izod impact strength Kg•cm/cm 2 β 23'C 2.8 1.3 β -40 * C 1.8 5 λverage grain size, microns 0.8 I ro 1 Blends 5, 6,8 used Nylon-6; blends 5, 6 included 8 wt.% e-caprolactam. 2 0.4 wt.% addition rate of maleic acid anhydride, MFR 50 g/10 min. 3 MFR 9g/10 min. . JIS K 7110 (with notch). TABU? Molded Product With Thermoplastic Resin of Blend Nos. 9, 29 and 30 Invention Comparative 21 30 2 Drop impact test β 6m 10 1 10 10 8m 10 10 9 10m 8 8 5 12m 5 5 0 ro ro The results show the number of tanks out of 10 that did not fail upon falling through the height. Although the invention has been described with reference to its preferred embodiments, those of ordinary skill in the art may, upon reading this disclosure, appreciate changes and modifications which do not depart from the scope and spirit of the invention as described above or claimed hereafter.

Claims: CLAIMS : 1. A thermoplastic resin composition comprising: (a) a polyolefin resin; (b) about 0.1 to about 5 wt.% of a polyamide, based upon the weight of the polyolefin resin, dispersed within said polyolefin resin; and (c) a polyolefin modified with an unsaturated carboxylic acid or its anhydride, said modified polyolefin being present in an amount not less than 0.2 times the amount of the polyamide. 2. The composition of claim l wherein said polyamide resin is dispersed as fine grains of average size less than about 4 μ in the polyolefin resin. 3. The composition of claim 1 wherein said polyamide resin is dispersed as fine grains of average size less than about 2 μ in the polyolefin resin. 4. The composition of claim 1 further comprising a plasticizer selected from the group consisting of e-caprolactam, N-butyl benzenesulfonamide or octyl-p-oxybenzoate in an amount from about 0.5 to about 40 wt.%, based upon the polyamide weight. 5. The composition of claim 1 further comprising additives selected from the group consisting of fillers, heat stabilizers, light stabilizers, flame retardants, anti-static agents, releasing agents, foaming agents, plasticizers and nucleating agents. 6. The composition of claim 1 wherein the polyolefin resin is selected from a polyethylene, having a high melt load index of greater than about 0.1 and a melt index of less than about 100, and a polypropylene, having a melt flow rate of about 0.01 to about 150. 7. A thermoplastic resin composition comprising: (a) a polyolefin resin selected from a polyethylene, having a high melt load index of greater than about 0.1 and a melt index of less than about 100, and a polypropylene, having a melt flow rate of about 0.01 to about 150; (b) about 0.1 to about 5 wt.% of a polyamide, dispersed as particles of less than about 4 μ average size within said polyolefin resin, based upon the weight of the polyolefin resin; and (c) a modified polyolefin in an amount not less than about 0.2 times the weight of the polyamide. 8. The composition of claim 7 wherein the average particle size of the polyamide is less than about 2 μ. 9. A method for producing a thermoplastic resin composition comprising: blending under melt conditions a mixture comprising: (a) a polyolefin resin; (b) about 0.1 to about 5 wt.% of a polyamide dispersed within said polyolefin resin, based upon the weight of the polyolefin resin; and (c) a polyolefin modified with an unsaturated carboxylic acid or its anhydride, said modified polyolefin being present in an amount not less than about 0.2 times the amount of the polyamide; for a time sufficient to disperse the polyamide as particles within the polyolefin resin. 10. The method of claim 9 further comprising adding a radical polymerization catalyst selected from the peroxides. 11. The method of claim 9 wherein the polyamide and modified polyolefin are melt blended together in a first step before blending with the polyolefin resin. 12. a method for producing a thermoplastic resin composition comprising: dissolving in an organic solvent while stirring a mixture comprising: (a) a polyolefin resin; (b) o.l to 5 wt.% of a polyamide dispersed within said polyolefin resin, based upon the weight of the polyolefin resin; and (c) a polyolefin modified with an unsaturated carboxylic acid or its anhydride, said modified polyolefin being present in an amount not less than 0.2 times the amount of the polyamide; and removing substantially all the solvent to obtain a thermoplastic resin product. 13. The method of claim 12 further comprising aάding a radical polymerization catalyst selected from the peroxides. 14. A multi-layered laminated molding product comprising: (i) an upper layer of thermoplastic resin comprising: - 28 - (a) a polyolefin resin; (b) about 0.1 to about 5 wt.% of a polyamide dispersed within said polyolefin resin, based upon the weight of the polyolefin resin; and (c) a polyolefin modified with an unsaturated carboxylic acid or its anhydride, said modified polyolefin being present in an amount not less than about 0,2 times the amount of the polyamide; (ii) a modified polyolefin layer laminated to one side of the upper thermoplastic resin layer; and (iii) a polyamide resin layer laminated to the modified polyolefin layer. _15« The molding product of claim 1 further comprising: (i) a second modified polyolefin layer laminated to the polyamide resin layer; and iii) a lower thermoplastic resin layer laminated to the second modified polyolefin layer.

Inventors: NOGATA TETSURO, TAKADO YUTAKA, NOGATA, TETSURO, TAKADO, YUTAKA
Applicants: TONEN SEKIYUKAGAKU KK, TONEN SEKIYUKAGAKU K.K.
Application year: 1990
Main classification: C08L77
IPC codes: B32B27, C08L23, C08L77