JPS6034461B2 - Method for manufacturing multilayer blow container - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing a multilayer blow container.

More specifically, the present invention relates to a method for manufacturing a multilayer blow container in which a polyolefin resin layer and a nylon resin or saponified ethylene acetate copolymer layer are laminated with an intermediate layer interposed therebetween. Additionally, nylon resin and saponified ethylene-vinyl acetate copolymer have excellent gas barrier properties, oil resistance,
Although this resin had excellent mechanical strength, it had drawbacks such as high price and high water permeability.

Although these resins have gas barrier properties and oil resistance that are inferior to the above two resins, they are not price competitive with vinyl chloride resins, which are cheaper, and have rarely been used as food packaging materials. In recent years, residual vinyl chloride monomer in vinyl chloride resin has become a problem, and laminates of nylon resin or ethylene-pynylacetate saponified polyolefin resin have attracted attention as an alternative to vinyl chloride resin as food packaging materials. There is. This laminate can have gas barrier properties, oil resistance, and water impermeability, so when used as a container for foods such as mayonnaise and soy sauce, the food can be stored for a long time.

On the other hand, polyolefin resins could not be used in applications other than food packaging materials, such as gasoline containers, due to poor oil resistance, but by using these laminates, oil resistance was improved and gasoline barrier properties were significantly reduced. improve,
It became possible to use it as a gasoline container. As mentioned above, the applications of laminates of polyolefin resin and nylon resin or saponified ethylene-vinyl acetate copolymer are expanding, but the affinity between polyolefin resin and the above two resins is low, and it is difficult to melt. It has the disadvantage that it cannot be easily bonded, and various methods have been proposed to impart adhesive strength.

As one example, JP-A No. 48-55270 discloses that a modified polyolefin resin obtained by graft polymerizing an unsaturated carboxylic acid or its anhydride to a crystalline polyolefin resin is used in a polyolefin resin layer to combine a polyolefin resin and a nylon resin. A method of coextrusion to obtain a multilayer blown container with excellent adhesive strength has been proposed.

However, in this method, if the burrs generated during molding of the multilayer blow container are collected and mixed with modified polyolefin resin or nylon resin for reuse, adhesive strength and impact strength are reduced. In large multi-layer blow containers such as gasoline tanks, a decrease in impact strength will greatly reduce the product value, and if burrs are not recovered, the cost of raw materials will rise significantly, making the containers extremely expensive for gasoline tanks. Become something. The inventors of the present invention have carried out extensive research in consideration of these issues, and have found that a modified ethylene copolymer with a degree of crystallinity of 2 to 30% is used as an adhesive layer, that is, a polyolefin resin layer and a resin or ethylene-vinyl acetate copolymer as an adhesive layer. By using it as an intermediate layer between the compound layers, it is possible to obtain a multilayer blow container with almost no decrease in adhesive strength or impact strength due to burr recovery, thus achieving the present invention. That is, the gist of the present invention is that when manufacturing a multilayer blow container in which a polyolefin resin layer and a layer of nylon resin or saponified ethylene vinyl acetate copolymer are thinly layered with an intermediate layer interposed therebetween by blow molding, as the intermediate layer, It is characterized by using a modified ethylene copolymer obtained by graft polymerizing 0.01 to 1% by weight of maleic anhydride to a copolymer of ethylene with a crystallinity of 2 to 30% and a Q-olefin having 3 or more carbon atoms. The invention consists in a method for manufacturing a multilayer blow container.

Hereinafter, to explain the present invention in detail, the polyolefin resin used in the polyolefin resin layer in the present invention has a crystallinity at a temperature of 20:00 (according to the description in J. Poly. Sci. XW, P17-26 (1955)). A crystalline polyolefin resin having a crystalline polyolefin resin of more than 30% (measured by X-ray method), particularly 35% or more is preferable.

Such crystalline polyolefin resins include high density polyethylene, medium density polyethylene, polypropylene,
Examples include polybutene-1, crystalline ethylene-propylene copolymer, poly4-methylbentene-1, crystalline ethylene-monovinyl acetate copolymer, and saponified crystalline ethylene-vinyl acetate copolymer. Of course, mixtures of two or more of these polyolefins can also be used. Preferred crystalline polyolefin resins have a density (ASTMD150
Measured by 5-67.

The same applies below) 0.940 to 0.975 high density polyethylene or crystalline polypropylene resin. Next, a modified ethylene copolymer was prepared by graft polymerizing 0.01 to 1% by weight of maleic anhydride to a copolymer of ethylene with a crystallinity of 2 to 30% and an extended olefin having 3 or more carbon atoms, which was used as an intermediate layer. (Hereinafter, it will simply be abbreviated as modified ethylene copolymer.

) is a copolymer (
Maleic anhydride monomer or polymer is chemically bonded to maleic anhydride monomer (hereinafter simply referred to as ethylene copolymer), and the amount of bonding is 0.01 to ethylene copolymer in terms of maleic anhydride monomer. ~1% by weight. If the bonding amount is less than 0.01% by weight, the interlayer adhesive strength of the multilayer blow container obtained by the method of the present invention is low;
If it exceeds 1% by weight, gel-like substances, color development, etc. will increase in the middle layer of the multilayer blow container, which is not preferable. Within this range, preferably 0.03 to 0.8% by weight. Here, as the ethylene copolymer, one having a crystallinity (according to the measurement method described above) at a temperature of 20 qo is 2 to 30%.

If the crystallinity of the ethylene copolymer is more than 30% or less than 2%, the impact strength of the multilayer blow container will be significantly reduced due to burr recovery, and if it is less than 2%, the moldability as an intermediate layer will be poor. descend. Examples of the Q-olefin having 3 or more carbon atoms as a copolymerization component include propylene, 1-butene, 1-bentene, 1-hexene, and 4-methylbentene-1. Among these, preferred are Q olefins having 3 to 8 carbon atoms, particularly propylene and butene-1. Such ethylene copolymers are produced by copolymerizing ethylene and Q olefin using a Ziegler-based catalyst, especially a catalyst consisting of a vanadium compound such as vanadium oxytrichloride or vanadium tetrachloride and an organoaluminium compound. be able to.

Therefore, the modified ethylene copolymer used in the present invention is
It can be produced by adding maleic anhydride to the above ethylene copolymer and causing graft polymerization according to a known method.

The process for causing the graft polymerization reaction may be a solution method or a slurry method, but economically it is preferably a melt mixing method.

When using the melt kneading method, the ethylene copolymer contains 0.01~
If 1% by weight of maleic anhydride and 0.1% by weight or less, preferably 0.001 to 0.05% by weight of organic peroxide are blended and melt-kneaded at 120 to 300 qC, the grafting efficiency is high. This is advantageous because a modified ethylene copolymer with no gel-like substance and good hue can be obtained. Next, the nylon resin used in the present invention is a linear polymer having an acid amide bond obtained by ring-opening polymerization of lactam, condensation polymerization of diamine and dicarboxylic acid, etc., and has an average molecular weight of, for example, 15,000 to 15,000.
60,000, [ri]=1.0 to 6.0 are used, specifically nylon 6, nylon 6.6, nylon 6.10, nylon 11, nylon 6111, nylon 6r, etc. Can be used.

A saponified ethylene-vinyl acetate copolymer is a product obtained by partially or almost saponifying the acetate groups of an ethylene-vinyl acetate copolymer to form hydroxyl groups, and its chemical composition is not limited, such as average molecular weight. 10,000 to 100,000,
Those with an ethylene content of 10 to 70 mol% are used,
Taking gas barrier properties, gasoline barrier properties, and film formability into consideration, the product obtained by saponifying an ethylene-vinyl acetate copolymer with an ethylene content of 60 to 20 mol% to a degree of saponification of 90% or more is preferable.

However, in the method of the present invention, a conventional method may be used to manufacture a multilayer blow molding container, for example, as described in Plastic Age, September 1976 issue 5.
Examples include the method described in pages 9 onwards or Packaging Technology, September 1974 issue, pages 102 onwards. Usually, the resin of each layer is plasticized separately using multiple extruders and extruded into the same die with concentric flow channels, and the thickness of each layer is made uniform within the die, and each layer is layered. The parison is then extruded into an apparently single-layer parison. Then, this parison is inflated from the inside in a mold using air pressure, and is brought into close contact with the mold and cooled at the same time to obtain the desired multilayer blow container. During the above-mentioned blow molding, usually 10 to 12 parts by weight of burrs are generated per 10 parts by weight of the multilayer blow molding container, but in the method of the present invention, this burr is mixed into the polyolefin resin layer or intermediate layer. , can be recovered and used, and there is almost no decrease in adhesive strength or impact strength due to this recovery and use. Incidentally, if burr is mixed into the layer of nylon resin or saponified ethylene-vinyl acetate copolymer, gas barrier properties and gasoline barrier properties will deteriorate, which is not preferable. When mixed in the polyolefin resin layer, the amount of burrs mixed is 20 parts by weight or less, preferably 5 to 5 parts by weight per 100 parts by weight of the polyolefin resin, and when mixed in the intermediate layer, the amount of burrs mixed in is 20 parts by weight or less, preferably 5 to 5 parts by weight, based on 100 parts by weight of the polyolefin resin. The amount is 3000 parts by weight or less, preferably 50 to 200 parts by weight, per 10 parts by weight of the copolymer.

If the amount of burrs is too large, the impact strength of the molded container and the interlayer adhesive strength will decrease, which is not preferable. Of course, burrs may be mixed into both the polyolefin resin layer and the intermediate layer. Incidentally, the burrs used in blow molding are usually pulverized into particles or powder using a polymer pulverizer, and then dry blended with polyolefin pellets or modified ethylene copolymer pellets at a predetermined weight ratio. For example, a V-shaped blender, Henschel mixer, etc. are used for dry blending. The thickness of each layer of the multilayer blow container varies depending on the use and is not particularly limited, but the thickness of the layer of nylon resin or saponified ethylene-pinyl acetate copolymer is 0.1 to 30% of the thickness of the polyolefin resin layer. A multilayer blow container is preferable from the economic point of view. Usually the middle layer 5
layer 5 of saponified nylon resin or ethylene-pinyl acetate copolymer, preferably 10 mm to 500 mm, polyolefin resin layer 3
It is selected from the range of 0 Buddha to 10 skin, preferably 50 Mu to 7 Willow. As described above, the multilayer blow container obtained by the method of the present invention takes advantage of its gas impermeability, gasoline barrier properties, and solvent resistance, and can be used as food containers, pharmaceutical packaging bottles, gasoline tanks, diesel oil tanks, pesticide bottles, drums, etc. Can be used.

In particular, it can be suitably used for gasoline tanks. Next, an example of the present invention and a comparative example to be compared thereto will be described.

It should be noted that the following examples are provided to aid understanding of the present invention, and the scope of the present invention is not limited thereby. In the examples, "MI" refers to the melt index according to ASTM D-12385, and "MFI" refers to the melt index according to ASTM D-123.
870 shows the melt flow index according to 870.

In addition, the maleic anhydride grafting rate was determined using the characteristic absorption 1790 arc-1 of the acid anhydride using an infrared absorption spectrum, and the amount of maleic anhydride monomer and/or polymer bonded to the ethylene copolymer was determined by It is expressed in weight % based on the polymer. Example 1 The ethylene content was 83 mol%, the propylene content was 17 mol%, and the crystallinity was 5 (J.poly.Sci.
Measured at 20o0 according to the description in 7-26 (1955).

The same applies below. ), a modified ethylene copolymer with a maleic anhydride grafting ratio of 0.4% by weight and an MI of 0.9 is used as an intermediate layer, and a flesh layer nylon resin [Novamid 1030A (Novamid is a registered trademark of Mitsubishi Chemical Industries, Ltd.)], outer layer high-density polyethylene [Novatec BR30
0 (Novatec is a registered trademark in the Mitsubishi Chemical Industries column) 7 parts by weight and burr recovery polymer (burr composition is 9% by weight of high-density polyethylene, 5% by weight of nylon resin, 5% by weight of modified ethylene copolymer) 30 parts by weight Multilayer blow molding consisting of three layers was performed using the blended product. The layer structure is a nylon resin layer of 40 mm, an intermediate layer of 40 layers, a polyethylene and burr recovery polymer layer of 720 mm, and the molding conditions are a die temperature of 220 oo.
, suction pressure fine G, molding cycle 1 morning sand, mold temperature 160
, the molding die is the same concentric die, die/core = 15 side? /
On the 9th side, the bottle container was an 800cc cylindrical bottle. The amount of burrs generated was approximately 30% of the bottle molded product. The resulting bottles were measured for side adhesive strength, drop strength, and gasoline permeability, and the results are shown in Table 1 along with the appearance.

In addition, the side adhesive strength (unit: ta'inch) is based on JISK
T-peel strength was measured in accordance with 6854. Drop strength (unit number of non-destructive bottles (units) / number of samples (units)) is calculated by the number of samples and the number of non-destructive bottles when a molded container is filled with 100% water and dropped from a height of 50m. Indicated. The degree of adhesion of the bottom weld was determined by visual inspection of interlayer peeling at the weld, and those with no peeling were evaluated as good.

The gasoline permeability (unit: y/y) was determined by filling a molded container with gasoline, leaving it at room temperature for 30 days at 20 oo, and then measuring the amount of gasoline permeated.

Example 2 In Example 1, the outer layer was a blend of parts by weight of high-density polyethylene 7 and parts by weight of burr recovery polymer 3, but instead of high-density polyethylene [Novatec BR300].
Multilayer blowing was carried out in exactly the same manner except that the weight was changed to 10 parts by weight.

The properties of the bottles are shown in Table 1.

Example 3 A modified ethylene copolymer with an ethylene content of 87 mol%
, maleic anhydride was graft-polymerized to an ethylene-butene-1 copolymer with a butene-1 content of 13 mol% and a crystallinity of 20, maleic anhydride grafting rate = 0.4% by weight, M
Multilayer blowing was performed in exactly the same manner as in Example 1, except that a modified ethylene copolymer with I=1.8 was used.

The properties of the bottles are shown in Table 1. Example 4 The inner layer nylon resin was replaced with saponified ethylene-vinyl acetate copolymer [GL
Multilayer blowing was performed in exactly the same manner as in Example 3, except that Resin E (trademark of Nippon Gosei Kagaku Co., Ltd.) was used.

The properties of the bottles are shown in Table 1. Comparative Example 1 In Example 1, the modified ethylene copolymer was replaced with a modified ethylene copolymer with maleic anhydride grafting rate = 1.5% by weight (ethylene content = 87 mol%, butene content = 13 mol%, crystallinity A multilayer blow container was manufactured in exactly the same manner except that maleic anhydride was graft-polymerized to an ethylene-butene-1 copolymer of :20.

This bottle has a brown color and many lumps that appear to be gel-like substances can be seen.

The properties of the pins are shown in Table 1. Comparative Example 2 In Example 1, the modified ethylene copolymer was replaced with a modified ethylene copolymer with a maleic anhydride graft ratio of 0.005% by weight (ethylene content = 87 mol%, propylene content = 13 mol%, crystalline A multilayer blow container was manufactured in exactly the same manner as in Example 1, except that maleic anhydride was graft-polymerized to an ethylene propylene copolymer having a chemical degree of 20.

The properties of the pins are shown in Table 1. Comparative Example 3 In Example 1, maleic anhydride was graft-polymerized to an ethylene propylene copolymer with an ethylene content of 94 mol% and a crystallinity of 40% as a modified ethylene copolymer.
A multilayer blow container was manufactured in the same manner as in Example 1, except that a modified ethylene copolymer with a maleic anhydride graft ratio of 0.4% by weight and an M12.0 was used.

The properties of the bottles are shown in Table 1. Comparative Example 4 In Example 1, maleic anhydride was graft-polymerized to an ethylene propylene copolymer with an ethylene content of 78 mol% and a crystallinity of 0% as a modified ethylene copolymer, with a maleic anhydride grafting ratio of 0.4. A multilayer blow container was manufactured in the same manner as in Example 1 except that a modified ethylene copolymer having a weight percent of M12.0 was used.

The properties of the bottles are shown in Table 1. Example 5 The same modified ethylene copolymer as in Example 3 was used as the intermediate layer, the inner layer was nylon resin [Novamid 1030A], the outer layer was 50 parts by weight of high-density polyethylene [Novatec BR300], and parts by weight of burr recovery polymer 5 (the burr composition was high density). Multilayer blow molding consisting of three layers was performed using a blend of 9% by weight of polyethylene, 5% by weight of nylon resin, and 5% by weight of modified ethylene copolymer.

Thereafter, a multilayer blow container was molded in exactly the same manner as in Example 1, but the amount of burrs generated was about 50% of the bottle molded product. The properties of the bottle are shown in Table 1. Example 6 20 parts by weight of the same modified ethylene copolymer as in Example 3, parts by weight of burr recovery polymer 8 [Flash composition is 5% by weight of high density polyethylene 9, 5% by weight of nylon resin, 5% by weight of modified ethylene copolymer ] was used as the middle layer, an inner layer of nylon resin [Novamid 1030A], and an outer layer of high-density polyethylene [/Vatec BR300]. Multilayer blow molding was performed.

Claims (1)

[Scope of Claims] 1. When manufacturing a multilayer blow container in which a polyolefin resin layer and a layer of nylon resin or saponified ethylene-vinyl acetate copolymer are laminated with an intermediate layer interposed therebetween by blow molding, as the intermediate layer, crystallized Multilayer blowing characterized by using a modified ethylene copolymer obtained by graft polymerizing 0.01 to 1% by weight of maleic anhydride to a copolymer of 2 to 30% ethylene and α-olefin having 3 or more carbon atoms. Container manufacturing method. 2 As the intermediate layer, a modified ethylene copolymer obtained by graft polymerizing 0.01 to 1% by weight of maleic anhydride to an ethylene-butene-1 copolymer or ethylene-propylene copolymer with a crystallinity of 2 to 30% is used. A method for manufacturing a multilayer blow container according to claim 1. 3. The method for manufacturing a multilayer blow container according to claim 1 or 2, wherein burrs during blow molding are mixed into the polyolefin resin layer or the intermediate layer. 4. The burr during blow molding is applied to the polyolefin resin layer, and the burr is 20% per 100 parts by weight of the polyolefin resin of the layer.
Claim 3: The amount of the mixture is 0 parts by weight or less.
A method for producing a multilayer blow container as described in Section 1. 5. The multilayer blow container according to claim 3, in which burrs during blow molding are mixed into the intermediate layer so that the amount of burrs is 3000 parts by weight or less per 100 parts by weight of the modified ethylene copolymer in the layer. Manufacturing method. 6 The thickness of the layer of nylon resin or saponified ethylene vinyl acetate copolymer is 0.1 of the thickness of the polyolefin resin layer.
The method for manufacturing a multilayer blow container according to any one of claims 1 to 5, wherein the content is 30%. 7. The method for manufacturing a multilayer blow container according to any one of claims 1 to 6, wherein the intermediate layer has a thickness of 10 to 500 μm.