JPH0244710B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a multilayer container using a resin composition with good impact resistance and moldability consisting of an ethylene-vinyl alcohol copolymer resin (hereinafter referred to as EVOH), an alcohol plasticizer, and boric acid or a borate salt. be. Containers can be used for foods, organic chemicals, pesticides,
A plastic packaging container for gasoline, etc., which has a multilayer structure containing at least one layer of the resin composition, and has excellent gas barrier properties and organic solvent resistance, as well as impact resistance and good moldability. The invention relates to a multi-layered container. For example, glass containers have conventionally been used for chemicals such as agricultural chemicals, but they are easily damaged and dangerous when handled, and the containers themselves are heavy, making them inconvenient for transportation. In response to this, plastic containers were developed in JP-A-53-61478 and JP-A-53-61478.
As shown in No. 61479, a multilayer container with an inner layer of nylon resin was developed, but the nylon resin did not have sufficient solvent resistance, and the chemicals filled in the container permeated through the wall and the contents were reduced. The dot was hot. Furthermore, as shown in JP-A-54-72271, when containers are made with an ethylene/vinyl alcohol resin as the inner layer, they exhibit much better solvent resistance than containers made of nylon resin, and the amount of permeation of the contents is reduced. rarely occurs. However, EVOH resin does not have sufficient impact resistance and has the drawback of low bottle drop strength. EVOH has excellent barrier properties such as chemical resistance, gas permeation resistance, and organic vapor permeation resistance, so it is used in a variety of fields by taking advantage of these properties, but it is limited by its low impact resistance. There are many things. In order to improve this point, various plasticizers have been studied in the past, such as JP-A-47-17850 (N-
Thermoplastic resin composition characterized by containing 2 to 40 parts by weight of N-di-lower alkylformamide), JP-A-17851-1985 (Sulfoxide compound 2 to 40 parts by weight)
Thermoplastic resin composition characterized by mixing 40 parts by weight), JP-A-51-20946 (Production method characterized by mixing 0.01 to 10 parts by weight of an organosilicon compound), JP-A-Sho 51-20946 (Production method characterized by mixing 0.01 to 10 parts by weight of an organosilicon compound) 53-37756 [3-methylpentane-1,3,5-triol and/or 2-(2-hydroxypropyl)propane-1,
Composition consisting of 3-diol], Special Publication 1977-
20979 (Thermoplastic resin composition comprising 2 to 40 parts by weight of a reaction product obtained by adding polyhydric alcohol and glycidyl ether in an equimolar ratio)
etc. are known. Also, when resin is extruded vertically downward from a die into a pipe shape, the pipe becomes thinner and stretches due to its own weight, which is called drawdown property.
EVOH inherently has this tendency, and when blow molding a single layer or multiple layers, it tends to be impossible to mold or cause significant thickness deviation, which often causes problems in the manufacturing process. Furthermore, if a plasticizer is added to improve the impact resistance, the drawdown property becomes even worse. Therefore, if EVOH mixed with a plasticizer is used, the impact resistance is improved, but there is a drawback that the reject rate of molded products increases due to the drawdown property. For many other resins, drawdown can be reduced by increasing molecular weight;
In the case of EVOH, it is difficult to increase the molecular weight and reduce the drawdown property. The present inventors have previously conducted various studies to improve the impact resistance of EVOH and to obtain a composition with excellent moldability such as drawdown property. As a result, the ethylene content was 25 to 50 mol%, and the degree of saponification was 96% or more.
By blending EVOH with a specific amount of alcohol-based plasticizer and a specific amount of boric acid or borate, it not only significantly improves impact resistance, but also improves moldability by suppressing the drop in drawdown properties. He discovered that it could be obtained, and filed a patent application for such a composition (Japanese Patent Application No. 109924/1983). Furthermore, as a result of various studies on manufacturing methods to improve its performance, we found that there is a close relationship between the order of compounding and the physical properties of the molded product.
It has been discovered that impact resistance and drawdown properties can be further improved by first sufficiently dissolving boric acid or a boric acid salt in an alcohol-based plasticizer, and then mixing (for example, kneading) with EVOH. Reached. Furthermore, it was obtained in this way
A multilayer bottle manufactured by a coextrusion method using an EVOH resin composition as at least one layer has less uneven thickness of the resin layer and has high drop strength. It was discovered that the deep-drawn molded product of the coextruded sheet used also has less uneven thickness and has high drop strength. That is, 100 parts by weight of an ethylene/vinyl alcohol copolymer resin with an ethylene content of 25 to 60 mol% and a degree of saponification of 96% or more, and an alcoholic plasticizer of 2 to 15%.
part by weight and 0.05 to 3 parts by weight of boric acid or a boric acid salt, and the boric acid or boric acid salt is dissolved in an alcohol plasticizer and then mixed with an ethylene-vinyl alcohol copolymer resin. This is a multilayer container with excellent impact resistance that includes at least one layer of the composition. The present invention will be explained in more detail below. The ethylene content of EVOH used in the present invention must be between 25 and 60 mol%; if the ethylene content is less than 25 mol%, the molding temperature will approach the decomposition temperature, making molding difficult. . When the ethylene content exceeds 60 mol%, EVOH's excellent oil resistance and other properties deteriorate, and its softening point also decreases, making it difficult to expect various applications. In addition, when the degree of saponification is 96 mol% or less, oil resistance
Gas permeability is reduced, making it unsuitable. EVOH also suitable for use in the present invention
Although its molecular weight varies over a wide range, the intrinsic viscosity [η] measured using a mixed solvent of 85% phenol and 15% water at 30°C is 0.05 to 0.15.
Molecular weights corresponding to the range /g are preferred. [η]
If it is less than 0.05, the mechanical strength of the molded article will also decrease, making it difficult to improve the impact resistance according to the present invention. [η]
If it is 0.15 or more, the viscosity of the resin is too high, and the effect of improving drawdown properties by uniform blending with a plasticizer and blending of boric acid or borate is not sufficient. The alcohol-based plasticizer used as a plasticizer in the present invention not only has good compatibility with EVOH and sufficient plasticizing effect, but also facilitates molding and achieves the desired purpose when used in combination with boric acid or borate. This is an important choice in order to obtain the desired effect. In addition, boric acid or boric acid salts are known as gelling agents for polyvinyl alcohol, but by combining them with an alcohol plasticizer in a specific amount and blending them into EVOH in a specific order, it is possible to create a resin composition. For the first time, it becomes possible to produce a resin composition with low drawdown properties, good moldability, sufficient impact resistance, and excellent solvent and oil resistance. Alcohol plasticizers used in the present invention include glycerin, diglycerin, 12-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 1,5 pentanediol, 3-methylpentane 1,3,5-triol, 2,5-hexanediol, 1,2,6-hexanetriol, diethanolamine, triethanolamine, diethylene glycol, 2-(2-
Hydroxypropyl) propane 1,3 diol, etc. can be used. The blending ratio of plasticizer is 2~
It is necessary that the content be between 15% by weight, and if it is less than 2 parts by weight, the impact resistance of the resin composition will be insufficient;
If the amount exceeds 15 parts by weight, the effect of improving drawdown properties due to the addition of boric acid or borate cannot be expected, and if the amount exceeds 15 parts by weight, the good compatibility with EVOH will be lost, leading to severe bleeding and stickiness to the molded product. arise. The blending ratio of alcohol plasticizer is 4 to 8.
% by weight is particularly preferred. Compounding agents for improving drawdown properties include:
Boric acid or borates are suitable as they give a uniform gelling effect to the alcoholic plasticizer and EVOH resin. Here, borates refer to hydrated sodium tetraborate, anhydrous sodium tetraborate, and other borates other than sodium. The decrease in drawdown properties is thought to be due to the gelling effect of boric acid or borate. Other gelling agents include organic peroxides, polyvalent isocyanates, polyfunctional epoxy compounds, and polyvalent carboxylic acids, but these cannot simultaneously satisfy drawdown properties and impact resistance, and The surface of the product is likely to become rough. The blending ratio of boric acid or borate needs to be 0.05 to 3 parts by weight. If it is less than 0.05 parts by weight, the drawdown property will be poor and the effect of the present invention will not be recognized, and if it is more than 3 parts by weight, gelation will progress too much or the reaction will not be uniform, resulting in surface roughness and uneven thickness of the molded product. This causes problems such as: From this point of view, the amount of boric acid or boric acid salt added is particularly preferably 0.15 to 1.0 parts by weight. Alcohol plasticizer and boric acid or borate
When blending into EVOH, the order is extremely important. That is, after first sufficiently dissolving boric acid or borate in an alcoholic plasticizer,
Must be mixed (e.g. kneaded) with EVOH.
In other words, contact between the EVOH resin and boric acid or borate without the intervention of an alcohol plasticizer must be avoided. In other words, it is possible to produce a composition with improved impact resistance and good moldability only by following the compounding order of the present invention. Not only does this cause significant variation in the improvement effect, but it also causes uneven thickness of the molded product and roughening of the surface of the molded product. The cause of this is not clear, but prior to the reaction between the hydroxyl group of EVOH and boric acid or borate, the hydroxyl group of the alcohol plasticizer reacts with boric acid or borate, and then the reaction product but
It is believed that the objects of the present invention are achieved by interacting with EVOH resins. This is also inferred from the fact that the object of the present invention is achieved only when an alcohol-based plasticizer is used as a plasticizer through interaction with boric acid or a borate salt. This phenomenon cannot be explained by simple physical effects such as local gelation of boric acid or borate salt and EVOH resin in a system that does not contain an alcoholic plasticizer, resulting in non-uniformity. The specific blending method is to add boric acid or a boric acid salt to an alcohol-based plasticizer heated to 60 to 80℃ and stir to fully dissolve, then add EVOH at a certain ratio to an extruder and knead. The most suitable method is to pelletize it. The multilayer container of the present invention has at least one layer of the composition obtained by the method described above, and is also made of thermoplastic resin such as polyolefin, polyamide, polyester, polyvinyl chloride, or a filler if necessary. It is a blow-molded container having one or more layers of the added composition and, if necessary, an adhesive layer between them. It also includes molded containers processed by deep drawing from sheets and injection molded containers, but the moldability improvement effect of the present invention is particularly suitable for manufacturing blow molded containers. These thermoplastic resin layers are protective layers for the EVOH composition layer,
The material is selected appropriately, taking into consideration the influence of water, strength, moisture permeability, etc. In this case, the processing method usually relies on coextrusion. Also, when molding containers, 1 or 2 shafts can be used.
It is also possible to use an axial stretching method in combination. Applicable
The layer of EVOH composition, i.e. the barrier layer, is
To provide a container that can be in any of the inner layer, middle layer, and outer layer, has little unevenness in thickness, has high impact resistance, so there is no risk of breakage, and there is no risk of loss of content due to permeation of the contents, such as organic drugs, through the wall surface. sell. Antifogging agents, antioxidants, non-alcoholic plasticizers, colorants, fillers, etc. can also be added to the composition used in the present invention, if necessary. The multilayer container of the present invention has excellent inherent chemical resistance,
Not only does it have a barrier function, but it also improves the drop strength, which is a drawback of EVOH resin, and can be manufactured efficiently without uneven thickness, so it can be applied to fields where conventional products were difficult to use. For example, various organic chemicals and agricultural chemicals, sublimation chemicals, petroleum products such as gasoline,
Furthermore, it can be used for edible oils and fats for the purpose of preventing oxidation, hollow bottles for foods such as miso, hard deep-squeezed molded products, etc. In addition, it can also be used for automobile parts that require oil resistance. EXAMPLES Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited by these Examples. The testing and evaluation methods in the experimental examples, working examples, comparative experimental examples, and comparative examples are as follows. Further, the amounts of plasticizer and boric acid or boric acid (boric acid salt) added are expressed as a ratio to the weight of EVOH. 1 MI In accordance with ASTM-D-1238, the resin flow rate for 10 minutes is shown when a load of 2160 kg is applied using a melt indexer. The measurement temperature is 190℃. 2 Izot impact strength Indicates the notched impact strength according to ASTM-D-256. The sample was made by injection molding (thickness and width: 1/2 inch x 1/2 inch) with a 1/10 inch notch, and was left at 20℃ and 65%RH for one week. Measured at 65%RH. 3 Drop test At 20℃, 65%RH, blow container (capacity
Immediately after filling the 500c.c. with 500c.c. of water, the lid is placed on the container, the height is changed, and the container is allowed to fall vertically onto the concrete floor. At each height, the same bottle is dropped up to 10 times and the number of times it does not break is shown. Find the average value using 10 bottles and round it to an integer. 4 Content reduction: Add 500 c.c. of xylene to a blow container (capacity 500 c.c.).
The sample was placed at 50°C for one month and the change in weight was measured. 5. Thickness unevenness of the bottle The thickness unevenness of the bottle body is shown as follows. In the case of a three-layer bottle, the necessary layers were peeled off and the uneven thickness of the bottle body was measured using a dial gauge. Small uneven thickness...Thickness unevenness of 0 to ±10% of the average thickness Medium...Thickness unevenness of ±10 to ±30% of the average thickness Large...Thickness unevenness of ±30 to ±50% of the average thickness Experimental Example 1 When charging EVOH with an ethylene content of 30 mol%, saponification degree of 99.5 mol%, and [η] of 0.10/g to a 40 mmφ extruder, diethylene glycol was added from the hopper port to diethylene glycol at a concentration of 7.5% to diethylene glycol.
Pelletization was carried out while dropping a solution in which % by weight of boric acid had been dissolved in advance to obtain a sample of an EVOH composition containing 8% by weight of diethylene glycol and 0.6% by weight of boric acid. This was used to perform injection molding, samples for Izod impact tests were taken, and impact strength was measured. Next, using this pellet, resin was extruded downward through a pipe having a diameter of 20 mm using a 40 mmφ extruder, and the thickness was measured at 3 cm and 10 cm from the tip of the pipe. The results are shown in Table 1. Comparative Experimental Example 1 Using the EVOH used in Experimental Example 1,
Boric acid and EVOH pellets were dry blended and kneaded into pellets using a 40 mmφ extruder to produce EVOH pellets containing 0.6% by weight of boric acid. Thereafter, diethylene glycol was blended with the boric acid-containing EVOH pellets in the same manner as in Experimental Example 1, and finally EVOH containing 8% by weight of diethylene glycol and 0.6% by weight of boric acid was prepared as in Experimental Example 1.
A sample of the composition was obtained. Regarding this, a test similar to that shown in Experimental Example 1 was conducted. The results are shown in Table 1. Comparative Experimental Example 2 Experimental Example 1 was added to the EVOH used in Experimental Example 1.
Diethylene glycol was blended in the same manner as above.
This blended pellet and boric acid were dry blended and kneaded into pellets in the same manner as in Comparative Experiment Example 1, and finally a sample of the EVOH composition containing 8% by weight of diethylene glycol and 0.6% by weight of boric acid as in Experimental Example 1 was prepared. Obtained. Regarding this, a test similar to that shown in Experimental Example 1 was conducted. The results are shown in Table 1. Comparative Experimental Example 3 A test similar to that shown in Experimental Example 1 was conducted using only the EVOH used in Experimental Example 1. The results are shown in Table 1. Comparative Experimental Example 4 When charging the EVOH used in Experimental Example 1 to a 40 mmφ extruder, a solution of 40% by weight of boric acid dissolved in diethylene glycol was added dropwise to pelletize it, and 8% by weight of diethylene glycol, A sample of an EVOH composition containing 3.2% by weight of boric acid was obtained. Regarding this, a test similar to that shown in Experimental Example 1 was conducted. The results are shown in Table 1. Experimental Example 2 When charging EVOH with an ethylene content of 45 mol%, saponification degree of 99.5 mol%, and [η] of 0.09/g to a 40 mmφ extruder, a water-containing solution of 10% by weight based on the glycerin was added to glycerin from the hopper port. Pelletization is carried out while dropping a solution in which sodium borate has been dissolved in advance, and 10% by weight of glycerin,
Contains 1.0% by weight of hydrated sodium tetraborate
An EVOH composition was obtained. Regarding this, Experimental Example 1
A test similar to that shown was conducted. Table 2 shows the results.
Shown below. Comparative Experimental Example 5 Using the EVOH used in Experimental Example 2,
Sodium tetraborate and EVOH pellets were dry blended and kneaded into pellets using a 40 mmφ extruder to produce EVOH pellets containing 1.0% by weight of sodium tetraborate. Thereafter, glycerin was blended into EVOH pellets containing sodium tetraborate in the same manner as in Experimental Example 1, and finally the same as in Experimental Example 2, 10% by weight of glycerin and 1.0% boric acid.
A sample of the EVOH composition containing % by weight was obtained.
Regarding this, a test similar to that shown in Experimental Example 1 was conducted. The results are shown in Table 2. Comparative Experimental Example 6 Experimental Example 2 was added to the EVOH used in Experimental Example 2.
Glycerin was added in the same manner as above. This blended pellet and sodium tetraborate were dry blended and kneaded into pellets in the same manner as in Comparative Experiment Example 5, and finally an EVOH composition containing 10% by weight of glycerin and 1.0% by weight of boric acid as in Experimental Example 2 was prepared. A sample was obtained. Regarding this, a test similar to that shown in Experimental Example 1 was conducted. The results are shown in Table 2. Comparative Experimental Example 7 A test similar to that shown in Experimental Example 1 was conducted using only the EVOH used in Experimental Example 2. The results are shown in Table 2.

[Table] As shown in Table 1, according to Experimental Example 1, even at the same blending ratio, the drawdown property was better compared to Comparative Experimental Examples 1 and 2, and by uniformly blending, Izod impact strength also has a high value.
The surface of the molded product also shows very good gloss.

[Table] As shown in Table 2, Experimental Example 2 shows good performance even at the same blending ratio. Example 1 The sample obtained in Experimental Example 1 and three types of resins, high-density polyethylene with an MI of 0.8 (product name: Mitsui Petrochemicals Hi-Zex 3000B) and adhesive resin (product name: Mitsui Petrochemicals: Admer NF500), were each used. The contents were co-extruded using three 40mmφ extruders so that the outer layer was about 800μ of high-density polyethylene, the middle layer was about 100μ of adhesive resin, and the inner layer was about 100μ of the composition obtained in Experimental Example 1. A blow-molded container with a capacity of 500 c.c. was made, and the uneven thickness of the body of the blow bottle, a drop test, and the weight reduction rate of the chemical content were investigated. The results are shown in Table 3. Comparative Example 1 A blow-molded container with a wall thickness of 1 mm and an internal capacity of 500 c.c. was prepared using only the high-density polyethylene used in Example 1. Table 3 shows the various test results. Comparative Example 2 Instead of the EVOH composition obtained in Experimental Example 1 as the innermost layer of the three-layer blow container shown in Example 1,
A blow-molded container with an internal capacity of 500 c.c. was prepared using the EVOH shown in Comparative Experiment Example 3 as a non-additive resin. Table 3 shows the various test results. Comparative Example 3 As the innermost layer of the three-layer blow container shown in Example 1, the EVOH composition shown in Comparative Experimental Example 1 (diethylene glycol 8% by weight, boric acid 0.6%) was used instead of the EVOH composition obtained in Experimental Example 1. A blow-molded container with an inner capacity of 500 c.c. Table 3 shows the various test results. Comparative Example 4 Content capacity using nylon 6 (Toray CM1031) instead of the EVOH composition obtained in Experimental Example 1 as the innermost layer of the three-layer blow container shown in Example 1
A blow molded container of 500 c.c. was made. Table 3 shows the various test results. Example 2 In the same manner as in Example 1, approximately 100μ of the sample of Experimental Example 1 was added to the outermost layer and adhesive resin was added to the middle layer using a coextrusion method.
A blow-molded container with an internal capacity of 500 c.c. was made, with a thickness of 100 μm and an innermost layer of high-density polyethylene of approximately 800 μm.
Table 3 also shows the results of a test similar to that of Example 1. This bottle had an extremely glossy appearance.

[Table] * Comparative Example 1 was carried out on the polyethylene layer.Example 2 was carried out on the outermost layer.As shown in Table 3, according to the present invention, there were no problems during bottle molding, and the drop test also satisfied the required performance. . Also, the weight loss when filled with xylene is much lower than with nylon and other manufacturing methods.

Claims (1)

[Claims] 1 Ethylene content 25-60 mol%, saponification degree 96%
The above ethylene/vinyl alcohol copolymer resins
100 parts by weight, 2 to 15 parts by weight of an alcoholic plasticizer, and 0.05 to 3 parts by weight of boric acid or a boric acid salt, and after the boric acid or boric acid salt is dissolved in the alcoholic plasticizer, ethylene vinyl alcohol is added. A multilayer container comprising at least one layer of a resin composition mixed with a copolymer resin.