JPS62297138A - Method for welding resin surfaces - Google Patents

Abstract

PURPOSE:To make it possible to perfectly seal resin surfaces in a short period of time by a method wherein the welding of a plurality of resin surfaces by ultrasonic wave is performed under the existence of lubricant in portions to be welded. CONSTITUTION:The welding of a plurality of resin surfaces by ultrasonic wave is performed under the existence of lubricant in portions to be welded. The above-mentioned method can be applied to all the thermoplastic resins and the effect is much when applied to comparatively soft and non-polar resin or polyolefin-based resin such as polyethylene or the like. Any material, which has an effect to give sufficient lubricity to the interfaces of materials to be welded and gives no bad effect to the quality of contents to be filled in a space sealed by welding, will do. Method for depositing such as coating, spraying, dipping and the like are exampled for the method for existentializing the lubricant in portions to be welded. Any spread will do unless no lubricant exists in the interfaces of the materials to be welded and the preferable spread is 0.01-100g/m<2>. Ultrasonic sealing is performed with a device, which gives the ultrasonic vibration of 15-40kHz, with the amplitude of 10-100mum to the materials to be welded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of welding resin surfaces using ultrasonic waves. More specifically, it relates to an ultrasonic welding method in which a lubricant is present in the part to be welded to obtain a complete bath bonded state in a short period of time.

[Conventional technology]

Traditionally, thermoplastic resin bottles, tubes, films,
For welding (hereinafter also referred to as sealing) resin surfaces such as sheets,
Heat sealing method and high frequency sealing method are mainly used. However, the heat sealing method uses heat to melt and press the resin, so it is difficult to obtain a beautiful finish due to burning of the resin (discoloration and carbonization in extreme cases) and shrinkage (deformation) of the sealing surface. Also, there was a drawback that it was difficult to seal the debris.

Furthermore, the high-frequency sealing method is based on the polarity of the resin (it applies exothermic melting action due to molecular motion), so there is a problem that it cannot be used with non-polar resins such as polyethylene and polypropylene.

In recent years, ultrasonic sealing methods have been increasingly adopted in place of these sealing methods.

The ultrasonic sealing method involves applying ultrasonic vibrations of 15 to 40 KH2 to 10 to 100μ while the welding surface of the material to be welded is crimped.
In this method, the welding material is applied to the welded material with an amplitude of m, and the welding surfaces of the welded material are sealed by friction 1 heat generation.

This method is applicable to welding all types of thermoplastic resins, has the characteristics of being able to seal out contaminants, giving a beautiful appearance to the sealing surface, allowing any pattern to be engraved on the sealing surface, and being energy-saving.

However, in order to obtain a perfect seal using this method, sufficient ultrasonic oscillation time must be used, resulting in production constraints.

In other words, in the case of a production line that automatically fills bottles and tubes with contents such as liquids and automatically seals them, the ultrasonic sealing device must move with the bottles and tubes during the sealing time, and in order to increase production speed, It was necessary to use a multiplex system in which multiple ultrasonic sealing devices were lined up on the same line.

Further, in the case of ultrasonic sewing of films and sheets, a sewing machine type ultrasonic sealing device is used, but the production speed of this device is limited to 20 m/min at most, and there are many difficulties in productivity.

[Problem that the invention seeks to solve]

As a result of research aimed at improving the production speed of resin welding using ultrasonic waves, the present inventors discovered that the lubricity between the interfaces of materials to be welded was an important factor, leading to the present invention.

[Means for solving problems]

The present invention resides in a method for welding resin surfaces, which is characterized in that when welding a plurality of resin surfaces using ultrasonic waves, the welding is carried out in the presence of a lubricant in the welded portions.

The present invention will be explained in detail below.

Although the present invention can be applied to all thermoplastic resins, it is most effective when applied to relatively soft non-polar resins such as polyolefin resins such as polyethylene and polypropylene.

The shape of the material to be welded used in the present invention is not particularly limited (it can be applied to things in the shape of a bottle, a tube, a film, a sheet, etc.).
The contents of the tube are optional, such as juice, jelly, food such as tofu, egg tofu, toothpaste, skin cream, etc.
Daily necessities such as hair cream, etc.

The lubricant used in the present invention is one that has the effect of providing sufficient lubricity to the interface of the material to be bathed and does not have an adverse effect on the quality of the contents filled in the space sealed by welding. If so, there are no particular limitations.

Examples of these include higher fatty acid amides, higher fatty acid esters, higher fatty acid metal salts, solutions and emulsions of various lubricants such as beef tallow dissolved in suitable solvents, rapeseed oil, salad oil, olive oil, linseed oil, lard, butter,
Examples include lubricating oils, mineral oils, animal and vegetable oils and fats such as grease, and mineral oils.

Methods for making the lubricant present in the welded area include, but are not limited to, methods such as coating, sprinkling, and dipping. According to the method of adhesion, the lubricant used can be used efficiently.

The coating amount may be as long as the lubricant is present at the interface between the welded materials, but is preferably α01 to 1009/-.

The ultrasonic sealing method referred to in the present invention is carried out using a device that applies ultrasonic vibrations of 15 to 40 KHz to materials to be welded with an amplitude of 10 to 100 μm.

The equipment consists of a power supply, converter, booster, horn, and anvil.

With the power supply, the converted electrical energy of 15-40 KHz is converted into mechanical energy by the converter and transmitted to the booster.

Mechanical energy with an arbitrary amplitude of 10 to 100 μm, selected depending on the type, shape and thickness of the thermoplastic material, is then obtained from an appropriately selected booster,
It is transmitted to the welding material through a resonator called a horn.

The material to be welded is sandwiched between a horn and a support called an anvil, and the welding surface of the material receives vibration from the horn, generates frictional heat, and is welded.

For welding the hotter and tube, a method is used in which the welded portion is held between a horn and an anvil, and ultrasonic vibration is applied to the horn side to weld.

In the case of ultrasonic sewing of films and sheets, the materials to be welded are sandwiched between rotatable welding rollers instead of the horn and anvil, and the films and sheets are welded while continuously moving.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples.

Example 1. Comparative Example 1 Resin is poured into a blow molding machine (Nippon Koutex V8/S type) that extrudes a parison pointing vertically downward, and after the parison is molded, it is inserted into a mold, blown into it, cooled, and then protruded from the container body. A 300 cc rectangular container with an injection port was blow molded. Next, this container was filled with soybean milk to the full extent of the container injection hole, and then the injection port was sealed with ultrasonic waves using an ultrasonic sealing device (manufactured by Punson Corporation, Power Supply Sodel 187F, Booster Model 103). At this time, the ultrasonic oscillation time is α11α2. α5. IIL was set at 4 seconds, and the sealing state of the container injection port at this time was evaluated.

The results are shown in Table-1.

In the evaluation, a case where the container injection port was completely sealed was marked with a circle, a case where the seal was incomplete and the contents of the container leaked was marked with a Δ, and a case where the seal could not be sealed at all was marked with an x.

In this example, the resin used was high-pressure low-density polyethylene (L
DPK) 80 parts by weight, MFR is 29/10 minutes, and density is (
L9199/cll linear low density polyethylene (L-
A container was blow-molded using a resin mixed with 20 parts by weight of LDI'E), and one coat of rapeseed oil was applied to the container injection port as a lubricant. Comparative Example 1 shows the evaluation of K, in which no lubricant was applied to the container.

Example 2. Comparative Example 2 Inflation film molding machine (PURAKO UX-5
5) to form a film with a thickness of 30 μm, stack two of these films and use a sewing machine type ultrasonic sealing device (
Ultrasonic sewing was performed using BUi-111 (manufactured by Brother Industries, Ltd.). At this time, the sewing speed (moving speed of the stacked films) was set to 15°20, 25. The sewing speed was set at 30 m/min, and the sealing state of the films after sewing was evaluated. The results are shown in Table-2. For evaluation, pull the films together by hand, and mark O if the films are completely sealed, mark Δ if the films peel off partially but do not separate, and mark X if they completely peel off. .

In this example, the resin used was LDPI with an MIFR of 29710 minutes and a density of α9219/ai! : Before forming the film using ultrasonic sewing.

The resin welding surface was coated with salad oil as a lubricant at a coating amount of 59/-. Comparative Example 2 is an evaluation of a film to which no lubricant was applied.

〔Effect of the invention〕

In the above-described method of bath-bonding a plurality of resin surfaces using VC ultrasonic waves, complete sealing of the resin surfaces can be achieved in a short time by using a lubricant in the welding area.

The present invention reduces sealing time, increases production speed,
It is possible to save energy by reducing the number of ultrasonic sealing devices in an automatic production line and reducing power consumption.

Claims (1)

[Scope of Claims] 1) A method for welding resin surfaces, characterized in that when welding a plurality of thermoplastic resin surfaces using ultrasonic waves, a lubricant is present in the parts to be welded. 2) The welding method according to claim 1, wherein the method of making a lubricant exist in the part to be welded is by adhesion. 3) The welding method according to claim 2, wherein the method of adhesion is spreading, coating, or dipping.