JPS6130982B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a plastic container with a hook, and more particularly, to a plastic container having a structure in which a hook and a container body are joined by a hot melt adhesive. BACKGROUND OF THE INVENTION Conventionally, bottle-shaped containers formed by biaxial stretch blow molding of plastics are known to have excellent pressure resistance, steel properties, transparency, gas barrier properties, and the like. When such a plastic container is filled with a content having a self-generating pressure, such as a carbonated beverage, the weakest part of the container in terms of strength is the bottom or its periphery. In order to increase the pressure resistance of this plastic container and also to make the container self-sustaining, for example,
As proposed in Publication No. 55-142433, the axial cross-section of the bottom of the blow-molded container body is made substantially circumferential or elliptical, and the hakama parts are fixed so as to surround the bottom of the container body. It is already known that In order to fix the Hakama parts to the container body, mechanical engagement means, adhesive means, heat fusion means, etc. can be used, but mechanical engagement means require a cumbersome and accurate molding operation. Additionally, there is a risk that the hakama parts may detach from the container body during rough handling during the distribution stage. In addition, heat fusing means is limited by the materials used for both materials. For example, if the container body is made of polyethylene terephthalate and the shell part is made of olefin resin, heat fusing itself is difficult; however, fusing the two is difficult. A combination of these has drawbacks such as deformation of the container body and loss of molecular orientation in the container body due to high-temperature thermal history. Among various adhesives, hot melt adhesive layer is
Although it has the excellent advantage of being easy to bond with, there are still many difficulties in using hot melt adhesives to bond plastic bottles and Hakama parts. In other words, conventional hot melt adhesives lack impact resistance at low temperatures, and if a bottle filled with contents at low temperatures or a bottle that has been refrigerated is subjected to a drop impact, the adhesive parts may separate from the container body. A tendency to easily fall off is observed. Furthermore, when this joint is exposed to relatively high temperatures, the adhesive strength between the two tends to decrease significantly, which is a serious problem. The present inventor has achieved the following by bonding the above-mentioned container body and the Hakama parts through both a soft hot melt adhesive layer and a hard hot melt adhesive layer, which are respectively arranged at independent positions in the surface direction. It has been discovered that a plastic container with a hook can be obtained that exhibits excellent impact resistance and adhesive strength under both low and high temperature conditions. That is, an object of the present invention is to provide a plastic container with a hook, in which the container body and the hook part are firmly bonded under both low and high temperature conditions, and which has excellent pressure resistance, self-supporting properties, and impact resistance. There is something to do. According to the present invention, there is provided a container body which is formed by blow molding plastic and whose bottom portion has a substantially circumferential or elliptical cross section; and a container body which surrounds the bottom portion of the container body. In this plastic container, the container body and the hakama parts are arranged at independent positions in the surface direction, and (i) the hardness at 0°C ( In this specification, hardness refers to the hardness measured by JIS-K-6301 spring hardness tester Type A) of 70 degrees or less, and (ii) a hard hot melt adhesive layer with a hardness of 10 degrees or more at 40°C. A plastic container is provided, characterized in that the plastic container is bonded via a hot melt adhesive layer. The present invention will be explained in detail below based on the accompanying drawings. In FIG. 1 showing the overall structure of the plastic container of the present invention, this plastic container consists of a container body 1 and a hook part 2. The container body 1 is formed by blow molding plastic and is integral with the body. It is equipped with a container mouth part 3 that is shaped like this.
The bottom portion 4 has a circumferential or elliptical cross section in the axial direction from the viewpoint of pressure resistance and impact resistance. On the other hand, the hakama part 2 is formed by thermoforming plastic and has a shape that surrounds the bottom 4 of the container body and gives the container body 1 self-reliance. The embodiment shown in FIG. 1 consists of a substantially vertical peripheral wall portion 5 and a central portion 6 that projects upward and constitutes a receiving seat. 1
support. According to the present invention, the container body 1 and the hakama part 2
and are bonded through a specific combination of hot melt adhesive layers. That is, the joint 7 of these parts,
That is, in this specific example, between the container body bottom 4 and the seat 6 of the Hakama component, as best shown in FIG. and a second hot melt adhesive layer 9 are provided. The first adhesive layer 8 is (i) 0°C
The second adhesive layer 9 is (ii) a hard hot melt adhesive layer having a hardness of 10 degrees or more at 40°C. Therefore, according to the present invention, by joining the container body bottom 4 and the Hakama component receiving seat 6 through two types of adhesive layers 8 and 9 arranged independently from each other in the direction of the adhesive surface, low temperature and At any high temperature,
It is possible to form a joint exhibiting excellent impact resistance and adhesive strength, which makes it possible to completely prevent the tendency of the hakama parts to separate from the container body. That is, the soft hot melt adhesive layer 8 is
The hard hot-melt adhesive layer 9 acts to prevent damage to the bonded portion due to drop impact at low temperatures, and on the other hand, to suppress reduction in adhesive strength due to cohesive failure in the hot-melt adhesive layer at high temperatures. Moreover, surprisingly, it has been confirmed that the bonding structure using multiple types of adhesives according to the present invention shows almost no decrease in adhesive strength even when subjected to repeated low-temperature impact and high-frequency exposure. It was done. In the present invention, the installation strength that can completely prevent the tendency of the Hakama component to separate from the container body is the adhesive strength that will not cause the Hakama component or the container to come off when a normal adult pulls or twists the Hakama component or the container, that is, the tensile strength described below. This means that the peel strength and shear peel strength are at least 15 kg and 86 kg cm or more, respectively. In the present invention, a soft hot melt adhesive has a hardness of 70 or less, particularly 50 or less at 0° C., and is generally composed of a thermoplastic elastomer as a base resin. Satisfactory low-temperature impact strength means, in the case of plastic containers for carbonated beverages, as shown in Example 1 below, after storing a container filled with carbonated beverages or saline for a certain period of time in an atmosphere of 0°C.
This means that the Hakama parts will not come off from the container body when dropped from a height of 300 ft onto a concrete or metal surface, either upright or at an angle of 30°. Relatively hard hot melt, which has a hardness of 70 or more at 0°C, cannot absorb the large impact when it collides with concrete or metal surfaces, so it is
Even in the case of hot melt, which originally has adhesive strength at temperatures (°C), it is unsatisfactory in terms of low-temperature drop impact.
The amount of hot melt applied is 0.3 to 0.5 per container.
It is most preferable that the hardness is 50 or less, considering the economical application amount of 1.5 g and the fact that the application amount is halved because two types of hot melts are used. Suitable thermoplastic elastomers include styrene (S),
It is a block copolymer in which a block consisting of an aromatic vinyl monomer such as vinyltoluene is combined with a block consisting of a conjugated diene such as butadiene (B) or isoprene (I). Suitable examples thereof include:
They are S-B-S block copolymers, S-I-S block copolymers, S-B radial teleblock copolymers, S-I radial teleblock copolymers, or a combination of two or more of these. In these block copolymers, the weight ratio of styrene block and butadiene or isoprene block is
It can vary within the range of 10:90 to 50:50. These block copolymers are commercially available under the trade names KRATON (Siel Chemical Company) and SOLPRENE (Philips Petroleum Company). On the other hand, hard hot melt adhesives are those with a hardness of 10 degrees or more, especially 20 degrees or more at 40°C, and are generally made of crystalline thermoplastic polymers such as monoolefin polymers, monoolefin copolymers, polyamides, and polyesters. Constructed using a combination of resins as a base resin. Considering the distribution stage of the container, heat resistance at a relatively high temperature of 40°C can be specifically determined using the scale of tensile peel strength and shear peel strength at 40°C, as shown in Example 1 below. I do. The tackiness of hotmelt increases as the temperature increases, so the tackiness with other materials increases, but the hotmelt itself becomes soft and loses its cohesive strength. As will be described later, the present inventor believes that even in the case of hotmelt, which originally has adhesive strength at room temperature (25°C), if the hardness becomes less than 10 at 40°C, the cohesive strength will be insufficient, so that an ordinary adult cannot twist the Hakama parts or the container. It was discovered that it could be easily removed by rubbing or pulling. A hardness of 20 or higher is most preferable, considering that the amount of application is halved due to the combined use of two types of hot melts and the economical usage amount. Examples of suitable base resins are ethylene-acetic acid copolymers (EVA), ethylene-ethyl acrylate copolymers (EEA), ethylene-acrylic acid copolymers (EAA), low molecular weight polyethylenes, ionomers (ionically crosslinked ethylene copolymer), copolymerized nylon, timer acid-based polyamide, saturated copolymerized polyester resin, etc., and these may be used alone or in combination of two or more. These soft or hard hot melt adhesives contain tackifiers, tackifiers, etc. according to known formulations.
Plasticizers, waxes, fillers, stabilizers, antioxidants, etc. can be added. Examples of the tackifier include one or a combination of two or more of rosin, modified rosin, terpene resin, modified terpene resin, petroleum resin, styrenic copolymer, and coumaron-indene resin, and these are the base resins. It is used in an amount of 20 to 50% by weight. Examples of waxes include paraffin wax, microcrystalline wax, synthetic wax, vegetable wax, etc., and these are used in an amount of 5 to 20% by weight based on the base resin. Examples of the plasticizer include phthalate esters, glycolic acid esters, polybutene, mineral oil, etc., and the plasticizer is used in an amount of 20 to 20% by weight based on the base resin. Furthermore, in order to reduce costs and reduce viscoelastic properties during melting, fillers such as talc, clay, perlite, etc. can be added, and furthermore, antioxidants such as sterically hindered phenols can be added. Returning again to FIG. 2, the soft hot melt adhesive layer 8 and the hard hot melt adhesive layer 9 are placed on either or both of the surfaces to be joined between the bottom of the container body and the hakama part, so that they are oriented in the surface direction. However, it is preferable that these be provided so as to be relatively uniformly distributed over the surfaces to be joined. In the embodiment shown in FIG. 2, the soft hot melt adhesive layer 8 and the hard hot melt adhesive layer 9 are applied in the form of a plurality of spots that are alternately adjacent to each other in the circumferential direction. In another embodiment shown in FIG. 3, a soft hot melt adhesive layer 8 and a hard hot melt adhesive layer 9 are applied concentrically in the form of links having different diameters. The amount of hot melt adhesive applied is generally 30 to
300 mg/cm ² , particularly in the range of 50 to 200 mg/cm ² , and the coating area should be determined by measuring the adhesive strength at room temperature (25°C) by the tensile peel strength measured by the method described in Example 1 below. adjusted to be at least 15Kg. In the present invention, plastics constituting the container body include thermoplastic saturated polyesters such as polyethylene terephthalate, olefin resins such as polyethylene and polypropylene, vinyl chloride resins, polycarbonate resins, etc. It is formed into the shape of a container body by blow molding or biaxial stretch blow molding. In melt blow molding, the plastic is extruded in the form of a parison into a split mold, the parison is pinched off by the split mold, and then the parison is expanded within the mold by blowing fluid to form a container body. In addition, in biaxial stretch blow molding, after a parison is formed from the plastic by extrusion molding or injection molding, the parison is heated to a stretching temperature, stretched in the axial direction, and circumferentially in a split mold by blowing fluid. It becomes a container body in which molecules are mixed in two axial directions. The container body can be made of a single resin as exemplified above, or can be made of a blend of a plurality of resins. Furthermore, a multilayer laminate structure such as polypropylene/ethylene-vinyl alcohol copolymer/polypropylene can also be adopted. It is important for the bottom of the container body to have a circumferential shape, an ellipse shape, or a combination of these shapes in terms of pressure resistance and impact resistance, especially from the viewpoint of pressure resistance and economic efficiency (amount of material used). The following formula: 1.3R≧m≧0.7R In the formula, R is the maximum radius (mm) of the bottom of the container in the direction perpendicular to the container axis in Figure 1, and m is the length of the bottom of the container (mm) passing through the central axis of the container. ) is shown. It is preferable that it is within the range of . In the present invention, the Hakama parts are formed by injection molding the same plastics as those exemplified for the container body, or by subjecting this plastic sheet to vacuum forming, press forming, pressure forming, plug assist forming, etc. The shape may be any shape as long as it surrounds the bottom of the container body, stably supports the container body, and provides self-reliance to the container body. In order to manufacture the plastic container with hooks of the present invention, the plurality of types of hot melt adhesives described above are used.
While in a molten state, it is applied separately to the inner surfaces that will serve as seats for the Hakama parts in the positional relationship described above. The adhesive can be applied by methods such as spraying with a gun, extrusion from a die, melting, and transfer from a roll. While the adhesive layer applied within the hakama part is still in a molten state, the bottom of the container body is pressed against the inner surface of the hakama part to complete the adhesion between the two. To promote adhesion, the bottom of the container body is subjected to preliminary treatments such as primer coating, anchoring agent coating, corona discharge treatment, ozone treatment, flame treatment, etc., and the bottom of the container body is preheated, or the container is heated immediately after molding. The body can be used for gluing. Such a pretreatment can of course also be carried out on the inner surface which will serve as a seat for the Hakama part prior to application of the adhesive. In the present invention, after bonding, the container with the hook is heated at a temperature of 20 to 50°C, particularly 25 to 40°C.
Aging for 24 hours results in a significant increase in bond strength. Thus, from the point of view of adhesive strength, it should be avoided to immediately fill a container with a hook with cold contents immediately after adhesion. The invention is illustrated by the following example. Example 1 The weight ratio of phenol/tetrachloroethane is
The intrinsic viscosity at 30℃ in a 50/50 mixed medium is
The moisture content of 0.1/g polyethylene thyrephthalate pellets was reduced using a dehumidifying hot air circulation dryer.
After sufficiently drying to 0.005% or less, use a one-stage PET (polyethylene thyrephthalate) stretch blow molding machine (ASB650) manufactured by Nissei ASB Machinery Co., Ltd. to form the biaxially stretched blown PET container shown in Figure 1. was formed. This container had a body diameter of 112 mm, a maximum shoulder diameter of 114 mm, a bottom radius (R) of 56 mm, a bottom height (m) of 56 mm, and a container height of 502 mm. Container internal volume (inner volume from the top of the container opening to a position 54mm below)
was 2000 c.c., the container weight was 66.3 g, and the average thickness of the container body was 0.31 mm. On the other hand, the melt index according to the measurement method based on ASTM-D-1238-57T was 15.0g/10min,
High-density polyethylene with a density of 0.955 g/cm ³ at 23°C was molded using a screw in-line injection molding machine with a built-in screw having an L/D (effective screw length/screw diameter) value of 18. In, D ₁ is 112mm, D ₂ is 84mm, D ₃ = 34mm, H is 62.5
A Hakama part with mm and l of 10 mm and weight of 28 g was formed. The inner radius of curvature of the seat 6 of this Hakama part has the same value as the outer radius of curvature (56 mm) of the container bottom 4. Next, the hardness at 0℃ determined by a JIS-K-6301 spring hardness meter is 80 degrees, the hardness at 40℃ is 45 degrees, the melt viscosity at 180℃ determined by a Bruckfield BM type viscometer is 1600 cps, and the base polymer is acetic acid. Vinyl content (wt%) is 40
% is 45% by weight of ethylene-vinyl acetate copolymer,
A total of 35% by weight of both rosin ester and aliphatic petroleum resin as a tackifying resin, 19.5% by weight of paraffin wax, and BHT as an antioxidant.
ethylene-vinyl acetate hard hotmelt A containing 0.5% by weight of
The hardness at 50℃ and the hardness at 40℃ is 8
The melt viscosity at 180℃ measured by the viscometer is
Samples were obtained by joining the following four types of containers and Hakama parts with rubber-based soft hot melt B having a 6000 cps base polymer and a combination of SIS block copolymer and SBS block copolymer. (1) Apply hard hot melt A using a Nordson hot melt applicator (a combination of a 5 type fusion machine and an H20A type gun with 4 orifices), setting the applicator tank to 177°C.
Set the hose to 177°C and the gun head to 180°C, and apply approximately 0.4 g (0.1
g/1 point) Within 2 seconds after application, as shown in Figure 1, the PET bottle and the Hakama parts are joined for 10 seconds under a vertical load of about 7 kg, and then the vertical load is removed. This container was left in an atmosphere of about 25°C for one day and night. (2) Completely the same as (1) above, except that soft hot melt B was used instead of hard hot melt A in (1) above, and the opening time of the orifice of the discharge gun was changed to make the application amount 0.4 g. The container and the Hakama parts were joined together under the same conditions and left in an atmosphere of about 25°C all day and night. (3) Two hot melt applicators were used for hard hot melt A and soft hot melt B, and the opening time of the orifice of the discharge gun was changed in order to make the discharge amount of hard hot melt A 0.2 g ( Under exactly the same conditions as in 1), apply two dots to the seat 6 of the Hakama part at symmetrical positions with respect to the center point of the Hakama part, as shown in Figure 2, and at the same time, dispense 0.2 g of soft hot melt B. As shown in Figure 2, the conditions were exactly the same as in (1) above, except that the opening time of the orifice of the discharge gun was changed.
The coating was carried out at a position symmetrical with respect to the center point of the Hakama part and at a position shifted by 90° on the same circumference as the application point of the hard hot melt A. After applying the hard hot melt A and the soft hot melt B at the same time as shown in Figure 2, the container and the Hakama parts are joined within 2 seconds in the same manner as in (1) above, and then I left it there for a day and night. (4) Hard hot melt A and soft hot melt B
300 g each was placed into the tank of the hot melt applicator, the tank temperature was set at 177°C, and when the temperature of the hot melt in the tank reached 177°C, the hot melt in the tank was stirred as thoroughly as possible with a glass rod. Next, set the hose to 177℃ and the gun head to 180℃, and after the temperature has risen sufficiently, reduce the discharge amount to 0.4℃.
Apply 4 points in exactly the same way as in (1) above, except that the opening time of the orifice of the discharge gun was changed in order to achieve
It was left in an atmosphere of about 25°C all day and night. The following three types of tests were conducted using the above four types of containers. (i) Low-temperature drop impact strength Fill a container with the saline solution from step 2 and seal it with an aluminum cap. Next, this container is kept in a freezer set at 0°C for 24 hours. Immediately after taking the container out of the freezer, it was vertically dropped from a height of 2 m onto a smooth concrete surface, and the number of detached Hakama parts into the container body was determined. (ii) Adhesive strength of hot melt Tensile peel strength is measured by connecting the top chuck of the container directly to the 500 kg load cell of the tensile testing machine and having a female thread that fits into the male thread of the neck of the container formed in this example. The upper circumferential edge of the Hakama part is circularly connected by the lower chuck, which has a hook shape that engages the upper circumferential edge of the Hakama part to be joined to the container molded in this example by inserting the lower chuck into which the cross head moves downward. At four points in the circumferential direction, tension was applied at a speed of 500 mm/min.
The force (Kg) with which the Hakama parts were detached from the container was measured. The shear peeling strength is determined by fixing the entire container with a fixing device that fits inside the entire inside of the seat 6 of the Hakama part 2 including the outer wall in FIG. The neck portion of the container was twisted using a torque wrench with a female thread at the tip that was fitted into the container, and the torque (Kg cm) at which the container was detached from the Hakama parts was measured. The four types of containers were left at 25° C. for 24 hours and their tensile peel strength and shear peel strength were measured using the above measurement method. (iii) Heat resistance After storing the above four types of containers at 40℃ for a day and night,
Immediately, tensile peel strength and shear peel strength were measured using the measurement method (ii) above. The results obtained in the above measurements are shown in Table 1 for the four types of bottles. As is clear from Table 1, the combination of the container and Hakama parts that uses the hard hotmelt and soft hotmelt of the present invention by applying them at independent positions can simultaneously satisfy drop impact strength at low temperatures and heat resistance. I understand. 【table】

[Brief explanation of the drawing]

Figure 1 is a structural diagram of the entire plastic container, Figure 2
The figure is a cross-sectional view of a Hakama part and a plan view showing an example of the present invention in which two types of hot melt are applied in spots on the seat of the Hakama part. FIG. 2 is a plan view showing an example of the present invention applied concentrically onto a seat of a Hakama component. 1... Container body, 2... Hakama parts, 3... Container mouth, 4... Container bottom, 5... Hakama parts peripheral wall, 6... Hakama parts receiver, 7... Container and Hakama parts Joint portion, 8... Soft hot melt, 9...
...Hard hot melt, 10...Hole for water handling.

Claims (1)

[Scope of Claims] 1. A container body which is formed by blow molding plastic and whose bottom has a substantially circumferential or elliptical cross section in the axial direction, and a container which surrounds the bottom of the container body. In a plastic container, the container body and the hakama parts are arranged at independent positions in the plane direction, and (i) at 0°C Hardness (JIS
- K-6301) is bonded via a soft hot melt adhesive layer with a hardness of 70 degrees or less and (ii) a hard hot melt adhesive layer with a hardness of 10 degrees or more at 40 degrees Celsius. A plastic container characterized by excellent high-temperature peelability.