JPH0366735A - Thermoplastic resin composition for laminated formed products - Google Patents

Abstract

PURPOSE:To obtain a thermoplastic resin composition for laminatings excellent in impact resistance by adding appropriate amounts of a modified polyolefin and a polyamide to a polyolefin and making the particle sizes of the polyamide smaller than a specific value. CONSTITUTION:On the basis of the resin components, (A) 0.1 to 5wt.% of a polyamide, preferably containing 0.5 to 40wt.% of a plasticizer such as epsilon- caprolactam, (B) more than 1/5, based on the amount of component A, of a polyolefin modified with 0.005 to 5wt.% of an unsaturated carboxylic acid or its derivative and (C) the remaining amount of a polyolefin, preferably a polyethylene of more than 0.1 high-load melt index and less than 100 melt index, a polypropylene of 0.01 to 150 melt flow rate are employed and component A is dispersed into particles of less than 4mum average size to give the subject thermoplastic resin composition for laminatings.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a thermoplastic resin composition for multilayer molded products, and in particular to a polyolefin for multilayer molded products having excellent ionic impact resistance and having a polyamide layer and a polyolefin layer. The present invention relates to thermoplastic resin compositions suitable for use as layers.

[Prior Art and Problems to be Solved by the Invention] Polyolefin resins are inexpensive and have high strength, so they are widely used in the manufacture of various containers. However, since polyolefin resins do not have sufficient gas barrier properties, they are unsuitable for use in fuel tanks such as gasoline. Therefore, various attempts have been made to blend polyamide resins such as nylon with excellent gas barrier properties with polyolefin resins to create thermoplastic resin compositions with excellent both mechanical strength and gas barrier properties. No. 54-123158,
No. 59-232135, No. 62-158739, No. 62-241938, No. 62-241941, etc.).

In addition, instead of blending the two, a so-called multilayer molded product has been proposed in which a polyamide resin layer is laminated on a polyolefin layer to improve gas barrier properties (Japanese Patent Laid-Open No. 54
-113678, 55-91634, 55-1
No. 21017, Special Publication No. 60-14695). In this case, since the adhesive strength between the polyolefin layer and the polyamide layer is extremely weak, a method is used in which a modified plastic layer, such as a polyolefin resin modified with an unsaturated carboxylic acid, is interposed between the two layers. .

When producing such multilayer molded products, it has been proposed to collect the paris produced during container molding and mix it with polyolefin for reuse.
No. 13678 and No. 55-91634>. However,
Simply blending a multilayer tL-shaped material into a polyolefin does not necessarily result in a thermoplastic resin composition having satisfactory adhesive strength and impact resistance. This is believed to be due to the low compatibility between polyolefin and polyamide. Since impact resistance is particularly important for fuel tanks and the like, a decrease in impact resistance will greatly impair commercial value. Furthermore, if the material is manufactured without recovering the material, the impact resistance can be maintained, but it is not possible to reduce the cost of raw materials, which is not preferable.

Therefore, in view of the above problems, an object of the present invention is to provide a thermoplastic resin composition with excellent impact resistance.
In particular, the object of the present invention is to provide a thermoplastic resin composition suitable for use as a polyolefin layer of a multilayer molded article having excellent impact resistance and having a polyamide layer and a polyolefin layer.

[Means to solve the problem]

As a result of intensive research in view of the above problems, the present inventor has discovered that by adding appropriate amounts of modified polyolefin and polyamide to polyolefin and reducing the dispersed particle size of polyamide in the resin composition to a predetermined size or less, polyolefin and polyamide can be combined. The present invention was completed based on the discovery that it is possible to suppress the peeling phenomenon at the interface with particles, thereby improving the impact resistance of the resin.

That is, the thermoplastic resin composition for a multilayer molded article of the present invention contains (a) 0.1 to 5% by weight of polyamide, and Q)) an unsaturated carboxylic acid of 115 or more in the amount of the polyamide, based on the resin component. or a derivative thereof, and (c) the remainder is substantially polyolefin, and the polyamide is dispersed in the resin composition in a granular state with an average particle size of 4 μm or less.

The present invention will be explained in detail below.

Polyamides used in the present invention include hexamethylene diamine, decamethylene diamine, dodecamethylene diamine, 2.2.4- or 2.4.4. -trimethylhexamethylenediamine, 1.3- or 1.4-
Aliphatic, alicyclic or aromatic diamines such as bis(T-minomethyl)cyclohexane, bis(p-aminocyclohexylmethane), m- or p-xylylene diamine, and adipic acid, speric acid, sebacic acid, Polyamide resins produced from aliphatic, alicyclic or aromatic dicarboxylic acids such as cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, 6-aminocaproic acid, 11-
Polyamide resins made from aminocarboxylic acids such as aminoundecanoic acid, 12-aminododecanoic acid, ε-
Examples include polyamide resins produced from lactams such as caprolactam and ω-dodecalactam, copolyamide resins made of these components, and mixtures of these polyamide resins. Specifically, nylon 6,
Examples include nylon 66, nylon Ik, nylon 12, and copolymers thereof. Furthermore, a copolymer of 50% by weight or more of these nylon resins and the other resins mentioned above can be used.

The molecular weight of the polyamide is preferably in the range of 3,000 to 200,000, particularly preferably in the range of 10,000 to 100,000.

In addition, in order to improve impact resistance, ε-caprolactam, N-butylbenzenesulfonamide, octyl p-oxybenzoate, etc. are added to the above polyamide as plasticizers.
．． It is preferable to contain it in an amount of 5 to 40% by weight. A more preferable content of plasticizer is 3 to 25% by weight.

In addition, the polyolefins used in the present invention include ethylene, propylene, butene-1, hexene-1,
4-Methylpentene-1, etc. (7) Homopolymers of α-olefins, copolymers of ethylene and propylene or other α-olefins, copolymers of two or more of these α-olefins, etc. It will be done. Among these, polyethylene and polypropylene such as low density polyethylene, linear low density polyethylene, medium density polyethylene, and high density polyethylene are preferred. It may also be a copolymer of polyethylene or polypropylene and the other polymers mentioned above, containing 75% by weight or more of polyethylene or polypropylene.

Polypropylene is not limited to a homopolymer, and random or block copolymers with other α-olefins containing a propylene component of 50 mol% or more, preferably 80 mol% or more can also be used. Comonomers copolymerized with propylene include ethylene and other α-olefins, with ethylene being particularly preferred. Therefore, the term "polypropylene" used herein is not limited to homopolymers of propylene, but should be understood to include copolymers as well.

When polyethylene is used as the polyolefin, its high load melt index (HLMl 19
0℃, 21.6kg load) is 0.1 g/10 minutes or more, and the melt index (formerly 190℃, 2.16kg
load) is preferably 100 g/10 minutes or less. More preferably, the high road melt index is 1
g/10 minutes or more, and the melt index is 50 g/
It takes less than 10 minutes. In addition, when using polypropylene, its melt flow) (MFR230℃, 2.1
6 kg load> is preferably in the range of 0.01 to 150 g/10 minutes, more preferably 0.1 to 75 g/10 minutes.

By using polyethylene or polypropylene having melt fluidity within such a range, the composition can be kneaded well and the polyamide particles can be uniformly dispersed.

The modified polyolefin used in the present invention is a polyolefin modified with an unsaturated carboxylic acid or its anhydride. Examples of unsaturated carboxylic acids or their anhydrides include monocarboxylic acids such as acrylic acid and methacrylic acid, dicarboxylic acids such as maleic acid, fumaric acid, and itaconic acid;
Examples include dicarboxylic anhydrides such as maleic anhydride, itaconic anhydride, and endic acid anhydride (anhydride/imic acid), with dicarboxylic acids and their anhydrides being particularly preferred.

Specifically, maleic anhydride or endic acid anhydride (
Particularly preferred are polyolefins modified with hymic anhydride).

In addition, as polyolefins modified with unsaturated carboxylic acids or their anhydrides, α
-It includes not only homopolymers of olefins but also copolymers with other α-olefins.

The content of unsaturated carboxylic acid or its anhydride in the modified polyolefin is preferably within the range of 0.005 to 5% by weight. Specifically, when modified with maleic anhydride, The content of maleic anhydride is 0.01 to 3% by weight, more preferably 0.1 to 1% by weight.
When Himic acid anhydride is used, the content is 0.015 to 4% by weight, more preferably 0.15 to 1% by weight.
, 5% by weight. If the amount of modification by maleic anhydride and himic anhydride is less than the above lower limit, the addition of the modified polyolefin will not have a sufficient effect on improving the compatibility between the polyamide and polyolefin, and if it exceeds the upper limit, the compatibility with the polyolefin will decrease. decreases.

In addition, in the case of the above content of the modified monomer, the molar ratio between the terminal amine of the polyamide and the carboxylic acid group in the modified polyolefin is 0.1 or more, which is preferable from the viewpoint of improving impact resistance.

The modified polyolefin can be produced by either a solution method or a melt-kneading method. In the case of the melt-kneading method, the polyolefin, unsaturated carboxylic acid for modification (or acid anhydride), and catalyst are charged into an extruder or twin-screw kneader, and the
The mixture is heated to a temperature of 0° C. and kneaded while melting. In the case of a solution method, the starting material is dissolved in an organic solvent such as xylene, and the solution is stirred at a temperature of 80 to 140°C. In either case, ordinary radical polymerization catalysts can be used as catalysts, such as benzoyl peroxide, lauroyl peroxide, di-tert-butyl peroxide, acetyl peroxide, tert-butyl peroxybenzoic acid, dicumyl peroxide, Peroxybenzoic acid, peroxyacetic acid, tert-butyl peroxypivalate, 2,5-dimethyl-
Peroxides such as 2,5-ditertiary-butylperoxyhexine and diazo compounds such as azobisisobutyroniol (IJ) are preferred. The amount of catalyst added is 1 part by weight per 100 parts by weight of unsaturated carforonic acid for modification or its anhydride.
~100 parts by weight.

In the resin composition of the present invention, based on the resin component,
The content of polyamide is 0.1-5% by weight, preferably 0
．． The content of the modified polyolefin is 1 to 3% by weight, and is 175 or more, preferably 1 to 4 times, the content of the polyamide, and the remainder essentially consists of polyolefin. By sufficiently kneading the polyamide and modified polyolefin at such a composition ratio, the average particle size of the dispersed particles of the polyamide in the resin composition can be reduced to 4 μm or less. The peeling phenomenon can be prevented.

If the polyamide content is less than 0.1% by weight, the effect of modifying the polyolefin is small, no improvement in impact resistance is observed, and
If it exceeds % by weight, the brittle nature of the polyamide deteriorates, and no improvement in impact resistance is observed.

Further, if the content of the modified polyolefin is less than 175% of the content of the polyamide, the compatibility between the polyolefin and the polyamide will not improve, and the peeling phenomenon between them cannot be suppressed.

Note that the smaller the dispersed particles of polyamide in the resin composition, the better the impact resistance. The average dispersed particle size of the polyamide is more preferably 2 μm or less.

The resin composition of the present invention has the above composition, but inorganic fillers, carbon black, etc. may be added to improve mechanical strength, heat resistance, etc.

At this time, it is preferable that the blending ratio of the resin composition of the present invention is 50% or more in terms of volume ratio at 23°C. When the content of additives such as inorganic fillers and carbon black exceeds 50% by volume, moldability decreases, making it difficult to manufacture molded products, and the mechanical strength also decreases.

The resin composition of the present invention may also contain other additives for the purpose of modification, such as heat stabilizers, light stabilizers, flame retardants, plasticizers, antistatic agents, mold release agents, blowing agents, and nucleating agents. etc. can be added.

The composition of the present invention can be obtained by kneading in a heated molten state using an extruder such as a single screw extruder or a twin screw extruder. Note that each component of the aforementioned set FIi, ξ, is
The mixture may be mixed in advance using a Henschel mixer or the like, and then this mixture may be melt-kneaded using an extruder or the like. In addition, when melt-kneading the composition, if there is a large difference in melt viscosity between the polyolefin or modified polyolefin and the polyamide, in order to further improve the dispersibility of the composition, the polyamide and modified polyolefin may be melt-kneaded in advance. , and then melt-kneaded with polyolefin.

Using the composition of the present invention, for example, a multilayer molded article having a layered structure as shown in FIG. 1 can be manufactured. Here, the multilayer molded product has a resin layer i 1 made of the composition of the present invention.
, a polyamide resin layer 2, and a modified plastic layer 3.3 that adheres both layers. Modified plastic layer 3.3
For example, if a modified polyolefin is used in the resin layer 11, the strength of the adhesion between each layer will be increased, and a multilayer molded product with high mechanical strength can be obtained.

If the polyamide layer 2 is used as an inner layer as shown in FIG. 1, the multilayer molded product will also have excellent water resistance.

Such a multilayer molded article can be manufactured, for example, by a blow molding method, and paris generated during the manufacturing process can be collected and kneaded into the resin forming the resin layer 1.1. PARI contains a polyolefin, a modified polyolefin, and a polyamide resin, which have the same composition as the composition of the present invention, so that they can be kneaded without deteriorating compatibility. The composition ratio of polyolefin, modified polyolefin, and polyamide resin in Paris will vary depending on the thickness of each layer of the multilayer molded product in which Paris has appeared, but if you take this into consideration and add resin as appropriate, it will be possible to regenerate Paris. It can be used without any problems and is economical.

[For production]

Although the compatibility between polyamide and polyolefin is poor, the two can be made compatible by interposing a polyolefin modified with an unsaturated carboxylic acid or the like.

In particular, in a polyolefin-based composition containing polyamide and modified polyolefin in a predetermined ratio, the average particle diameter of the polyamide dispersed in the composition is 4.
By making the thickness smaller than μm (1), it is possible to prevent the occurrence of a peeling phenomenon at the polyamide particle interface. Further, the carboxylic acid group of the modified polyolefin and the terminal amine of the polyamide resin react, and a polyamide-modified polyolefin copolymer is uniformly produced in the resin. It is thought that the impact resistance of the resin composition is improved for the above two reasons.

〔Example〕

The present invention will be explained in more detail with reference to the following examples.

Examples 1 to 6 Nylon 6 with a number average molecular weight of 30,000 and containing 8% by weight of ε-caprolactam as a plasticizer, an addition rate of maleic anhydride of 0.4% by weight, and a melt index (old) of 0.4 g/10 min modified polyethylene with a density of 0.955 g/cm3 and a melt index (old) of 0.
, 5 g/10 minutes of polyethylene were triblended using a high speed mixer at the blending ratios shown in Table 1. Thereafter, it was put into a screw extruder and kneaded at 240°C to obtain composition pellets.

After drying the obtained composition pellet in a drying oven, a test piece was prepared by injection molding. Note that the cylinder temperature during injection molding was 240°C. Tensile impact tests were conducted at 23°C and -40°C according to the STM 01822-3 method. The results are shown in Table 1.

Examples 7 to 14 Compositions were prepared using the nylon shown in Table 1 and the same modified polyethylene and polyethylene as in Example 1 at the blending ratios shown in Table 1. A test piece was prepared in the same manner as in Example 1, and a tensile impact test was conducted.

The results are shown in Table 1.

Comparative Examples 1 to 4 For comparison, compositions were prepared using the polyamide shown in Table 2 and the same modified polyethylene and polyethylene as in Example 1, each having the blending ratio shown in Table 2. A test piece was prepared in the same manner as in Example 1, and a tensile impact test was conducted. The results are shown in Table 2.

Examples 15-20 Nylon 6 with a number average molecular weight of 30,000 and containing 8% by weight of ε-caprolactam, an addition rate of maleic anhydride of 0.4% by weight, and an MFR (230°C, 2.16 kg load) of 50 g / 10 minutes modified polypropylene and MF
1. Using a polypropylene homopolymer with an R of 9 g/10 min. A composition was prepared in the same manner as in Example 1, using the blending ratios shown in Table iJ3. A test piece was then prepared in the same manner as in Example 1. At 23°C and -20°C, J
An Izot impact test was conducted according to the IS K-7110 method. The results are shown in Table 3.

Examples 21 to 28 Compositions were prepared using the nylon shown in Table 3 and the same modified polypropylene and polypropylene as in Example 15 at the blending ratios shown in Table 3. A test piece was prepared in the same manner as in Example 15, and an Izot impact test was conducted.

The results are shown in Table 3.

Comparative Examples 5 to 8 For comparison, polyamides shown in Table 4 and Example 15
Compositions were prepared using the same modified polypropylene and polypropylene as shown in Table 4, respectively.

A test piece was prepared in the same manner as in Example 15, and
An Izot impact test was conducted in the same manner as above. The results are shown in Table 4.

As is clear from the above, the test piece of this example has high values for both tensile impact strength and isot impact strength.

Example 29 Using the composition in Example 2, nylon 6, and modified polyethylene, a fuel tank having a capacity of 70 A and consisting of five layers of three types as shown in FIG. 1 was molded by blow molding.

Here, the innermost layer and the outermost layer (layer 1.1 in FIG. 1) are coated with Example 2.
In the composition, nylon 6 was used for the intermediate layer (layer 2 in the 11th m) and modified polyethylene was used for the adhesive layer (layer 3.3 in FIG. 1).

The thickness of each layer was 100 μm for the outermost layer and innermost layer made of the composition of Example 2, 1800 μm 1 and 1840 μm 1 for the intermediate layer made of nylon 6, and 120 μm for the adhesive layer of modified polyethylene.

A drop impact test was conducted on this fuel tank in the following manner.

Fill the fuel tank with water of a weight equal to the weight of fuel to fill the fuel tank, drop 10 fuel tanks from each height shown in Table 5, and determine whether or not the fuel tank has been destroyed. Examined. The results are shown in Table 5.

Example 30 Recovered Paris 10 during fuel tank molding in Example 29
The layer structure is the same as in Example 29, except that a blend of 0 parts by weight and 100 parts by weight of the composition of Example 2 (average particle size of polyamide 0.5 μm) is used as the innermost layer and outermost layer of the fuel tank. A fuel tank (volume 701) with three types and five layers was also molded in the same manner as in Example 29.

A drop impact test was conducted on the obtained fuel tank in the same manner as in Example 29. The results are shown in Table 5.

Comparative Example 9 The same layer structure as Example 29 was used, except that high-density polyethylene (density 0.955, melt index 0.5 g/10 min) was used as the innermost layer and outermost layer of the fuel tank. A fuel tank (volume 701) was similarly molded.

A drop impact test was conducted on the obtained fuel tank in the same manner as in Example 29. The results are also shown in Table 5.

Table 5 [Effects of the Invention] As detailed above, the thermoplastic resin composition of the present invention has excellent impact resistance. This is thought to be because the polyamide was dispersed in fine particles in the polyolefin, which prevented peeling at the interface between the polyamide and the polyolefin.

When a multilayer molded product is manufactured using the composition of the present invention and polyamide, the adhesive strength between the modified polyolefin layer provided between both phase resin layers and the layer of the composition of the present invention is sufficiently high, so that impact resistance is improved. It is possible to produce a multilayer molded product that has excellent properties and mechanical strength. Note that the paris produced as a by-product in the manufacturing process of this multilayer molded article can be mixed into the resin composition of the present invention and reused, which is economically advantageous.

Since the composition of the present invention has the above-mentioned properties, multilayer molded products using the same are suitable for various industrial materials, particularly fuel tanks, automobile parts, home appliance parts, etc.

[Brief explanation of drawings]

FIG. 1 is a partial cross-sectional view showing an example of the layer structure of a multilayer molded product manufactured using the resin composition of the present invention. ■ Layer 2 made of the composition of the present invention Polyamide layer 3 Modified polyolefin layer Applicant: Tonen Petrochemical Co., Ltd.

Claims (4)

[Claims] (1) Based on the resin component (a) Polyamide 0.1~
5% by weight, (b) a polyolefin modified with an unsaturated carboxylic acid or a derivative thereof in an amount of 1/5 or more of the blended amount of the polyamide, and (c) the remainder substantially consisting of a polyolefin. 1. A thermoplastic resin composition, wherein the polyamide is dispersed in the resin composition in a granular state with an average particle size of 4 μm or less. (2) In the thermoplastic resin composition according to claim 1,
A thermoplastic resin composition, wherein the polyolefin is polyethylene having a high road melt index of 0.1 or more and a melt index of 100 or less. (3) In the thermoplastic resin composition according to claim 1,
The polyolefin has a melt flow rate of 0.01
A thermoplastic resin composition characterized in that it is a polypropylene having a molecular weight of 150 to 150. (4) In the thermoplastic resin composition according to claim 1,
A thermoplastic resin composition characterized in that the polyamide contains 0.5 to 40% by weight of a plasticizer.