JP2021109319A - Welding method of thermoplastic resin molded products - Google Patents

Abstract

To provide a welding method of thermoplastic resin molded products, capable of easily setting conditions, while suppressing thermal damage, and continuously welding thermoplastic resin molded products each other with high productivity and energy saving.SOLUTION: Provided is a welding method of thermoplastic resin molded products in which a feed rate and a photon density of infrared rays to be irradiated are controlled within a range above a straight line p and below a straight line q of a graph showing the relation between a feed rate v (mm/s) and a photon density P (photons/mm2-s) obtained in a specific process to be performed in advance by regarding, as P, the photon density of the infrared rays that can weld the molded products together by infrared ray irradiation at the feed rate v without causing burning or deformation on the infrared ray irradiation side of the molded product, when at least two thermoplastic resin molded products are arranged in contact with each other and furthermore a heat radiating material is arranged in contact and the infrared rays are irradiated while scanning from the heat radiating material side so as to weld the molded products together.SELECTED DRAWING: Figure 2

Description

The present invention relates to a method for welding a thermoplastic resin molded product.

As a welding method between thermoplastic resin molded bodies such as a thermoplastic resin film, an ultrasonic welding method, a high frequency welding method, an infrared welding method and the like are known. In the ultrasonic welding method, when the thermoplastic resin constituting the molded body is a soft resin or a fluororesin having a small friction coefficient, the ultrasonic energy is easily attenuated and welding is often difficult. Further, the high frequency welding method is often difficult to apply to general-purpose resins such as polyethylene, polypropylene, and polystyrene polyester, which have low dielectric loss, and fluororesins.

The infrared welding method is a method of heating and melting a welded portion using infrared rays to weld the welded portion. However, thermal damage such as burning is likely to occur on the surface of the molded product on the side irradiated with infrared rays. Therefore, a method has been proposed in which thermoplastic resin molded bodies are placed in contact with each other, and an infrared-transparent heat-dissipating material is placed in contact with the molded body on the side to be irradiated with infrared rays, and then irradiated while scanning infrared rays for welding. (For example, Patent Document 1).

Japanese Patent No. 4279674

However, in the conventional infrared welding method using a heat radiating material as in Patent Document 1, it is difficult to set the conditions, and the sending speed of the infrared rays to be scanned is several mm / s, which is inferior in productivity. In addition, energy saving is also important in welding between thermoplastic resin molded bodies.

INDUSTRIAL APPLICABILITY According to the present invention, a thermoplastic resin molded product capable of continuously welding thermoplastic resin molded products with high productivity and energy saving while suppressing thermal damage such as burning of the outermost surface and the welded portion can be easily set. It is an object of the present invention to provide a welding method.

The present invention has the following aspects.
[1] At least two infrared-absorbing thermoplastic resin molded bodies are arranged in contact with each other, and a heat-dissipating material is contact-arranged on the outer surface of the thermoplastic resin molded body on the outer side of one of the heat-dissipating materials. Is a method of welding the thermoplastic resin molded bodies to each other by irradiating while scanning.
The feed rate of the infrared rays to be scanned is v (mm / s), and the photon density of the infrared rays is P (photons / mm ² · s). A thermoplastic resin molded body that controls the infrared ray feeding rate and photon density to be irradiated within the range above the straight line p and below the straight line q in the graph showing the relationship between the velocity v and the photon density P. Welding method.
Step (a): The heat-dissipating material is contact-arranged on the outer surface of the thermoplastic resin molded body on the outer side of one of the test pieces in which the thermoplastic resin molded bodies to be welded are arranged in contact with each other, and the heat-dissipating material side. The test of irradiating the thermoplastic resin molded body while scanning the infrared rays to confirm the welding state was repeated while changing the conditions, and the thermoplastic resin molded body in contact with the heat radiating material was not burnt or deformed on the side to be irradiated with the infrared rays. _{The minimum value v 1} of the feed rate v at which the thermoplastic resin molded bodies are welded to each other and the minimum photon density P _{1 at that time, and the maximum value v 2} of the feed rate v and the maximum photon density P _{2 at} that time are set. Ask.
Step (b): Point A (v ₁ , P ₁ ) and point B (v ₂ , P ₂ ) are plotted on a graph showing the relationship between the feed rate v and the photon density P, and a straight line passing through the points A and B. Let be a straight line k.
Step (c): Among the point at which the thermoplastic resin molded article in the test of the graph has not been welded, the below side of the straight line k, and most distance point close C to the straight line k (v _3, Let the straight line p be a straight line obtained by moving the straight line k in parallel to P ₃ ) (where v ₃ > v _2).
Step (d): Of the points where the thermoplastic resin molded product was whitened in the test in the graph, points D (v ₄ , P ₄ ) above the straight line k and closest to the straight line k. (However, the straight line obtained by moving the straight line k in parallel up to _{v 4} <v _{1) is defined as the straight line q.
[2] On the straight line k, the maximum value v 5 of the} feed rate v capable of welding the thermoplastic resin molded bodies to each other without causing bubbles, whitening and blackening in the thermoplastic resin molded body in the test. The method for welding a thermoplastic resin molded product according to [1], wherein the method for welding the thermoplastic resin molded product according to [1], wherein the method for welding the thermoplastic resin molded product according to [1], which controls the feeding speed and photon density of the infrared rays irradiated in the range where the feeding speed v is v ₁ or more and v _{5 or less.}
[3] to weld the thermoplastic resin molded bodies using a welding apparatus provided with a notifying means for notifying it when the feed speed of the infrared is v ₅ or more, the thermoplastic resin described in [2] Welding method of molded product.

According to the present invention, it is easy to set conditions, and while suppressing thermal damage such as burning of the outermost surface and the welded portion, thermoplastic resin molding capable of continuously welding thermoplastic resin molded bodies with high productivity and energy saving. A method of welding the body can be provided.

It is sectional drawing which showed an example of the welding method of the thermoplastic resin molded article of this invention. A graph in which the minimum feed rate v ₁ and the minimum photon density P ₁ (point A) and the maximum feed rate v ₂ and the maximum photon density P ₂ (point B) are plotted and connected by a straight line k is shown. It is a figure. It is a figure which showed the state which _{the maximum value v 3} of the feed rate and the photon density P ₃ (point C) were plotted on the straight line k of the graph of FIG. It is sectional drawing which showed another example of the welding method of the thermoplastic resin molded article of this invention.

In the method of welding a thermoplastic resin molded body of the present invention, at least two infrared-absorbing thermoplastic resin molded bodies are arranged in contact with each other, and a heat radiating material is brought into contact with the outer surface of one of the outer thermoplastic resin molded bodies. This is a method in which the thermoplastic resin molded bodies are welded to each other by arranging them and irradiating them while scanning infrared rays from the heat radiating material side under specific conditions.

Hereinafter, an example of an embodiment of the welding method for the thermoplastic resin molded product of the present invention will be shown and described with reference to the drawings. It should be noted that the dimensions and the like of the figures illustrated in the following description are examples, and the present invention is not necessarily limited thereto, and the present invention can be appropriately modified without changing the gist thereof. ..

In the welding method of the present embodiment, as shown in FIG. 1, a film-shaped infrared-absorbing first thermoplastic resin molded body 10 (hereinafter, referred to as “first molded body 10”) and a film-shaped first thermoplastic resin molded body 10 (hereinafter referred to as “first molded body 10”) The infrared-absorbing second thermoplastic resin molded body 20 (hereinafter referred to as “second molded body 20”) is referred to as a first surface 10a of the first molded body 10 and a first surface of the second molded body 20. Arrange so that they come into contact with 20a. Further, the plate-shaped heat radiating material 30 is arranged so as to come into contact with the second surface 10b on the side opposite to the first surface 10a of the first molded body 10.

In the state where the second molded body 20, the first molded body 10, and the heat radiating material 30 are laminated in this order, infrared rays I generated from the light source 110 included in the welding device 100 are emitted from the heat radiating material 30 side to the first molded body. Irradiation is performed while scanning in the plane direction of the first plane 10a of 10. Infrared I is absorbed by the welded portion where the first surface 10a of the first molded body 10 and the first surface 20a of the second molded body 20 are in contact, and the temperature of the welded portion rises to the softening temperature to melt. , The first molded body 10 and the second molded body 20 are welded. When the softening temperature of the first molded body 10 and the softening temperature of the second molded body 20 are different, welding occurs by heating the welded portion to at least the lower softening temperature by absorption of infrared rays I.

The softening temperature is a temperature at which the resin softens or melts, and is generally a melting point in the case of a crystalline thermoplastic resin and a glass transition temperature in the case of an amorphous thermoplastic resin. The melting point and glass transition temperature are measured by a differential scanning calorimetry device (DSC).

In the present embodiment, the heat radiating material 30 is arranged on the side that irradiates the infrared ray I, that is, on the second surface 10b side of the first molded body 10, so that the infrared ray I is on the second surface 10b side of the first molded body 10. A part of the heat generated by the absorption of the heat is absorbed by the heat radiating material 30 and dissipated. Thereby, at the time of welding, it is possible to suppress overheating of the surface layer on the second surface 10b side of the first molded body 10 while melting the resin of the welded portion of the first molded body 10 and the second molded body 20. Therefore, thermal damage such as burning on the second surface 10b side of the first molded body 10 is suppressed.

The method of scanning the infrared ray I with respect to the first molded body 10 and the second molded body 20 is not particularly limited, and for example, the light source 110 is moved while the first molded body 10 and the second molded body 20 are fixed. An example can be illustrated of a method of irradiating infrared rays I while allowing the members to irradiate the infrared rays I. Further, a method of moving the first molded body 10 and the second molded body 20 while irradiating infrared rays I from the fixed light source 110 may be used. A method of irradiating infrared rays I while moving the light source 110 and the first molded body 10 and the second molded body 20 with each other may be used.
The heat radiating material 30 at the time of welding may be in contact with the second surface 10b of the first molded body 10 so as not to move, or even if the heat radiating material 30 and the first molded body 10 are slidable. good.

The mechanism for holding the laminated heat radiating material 30, the first molded body 10, and the second molded body 20 is not particularly limited, and for example, a mechanical clamp mechanism using a screw type clamp, a spring, a hydraulic pressure, an air pressure, or the like is used. It can be exemplified.

Hereinafter, a method for controlling the feeding speed and photon density of infrared rays I irradiating the first molded body 10 and the second molded body 20 will be described.
The following steps, where the feed rate of infrared rays I scanned in the plane direction of the second surface 10b of the first molded body 10 is v (mm / s) and the photon density of infrared rays I is P (photons / mm ² · s). (A) to (d) are carried out in advance.

(Step (a))
The heat radiating material 30 is placed on the second surface 10b (outer surface) of the first molded body 10 of the test body in which the first molded body 10 and the second molded body 20 (thermoplastic resin molded bodies) to be welded are arranged in contact with each other. Is arranged in contact with each other, and the test of irradiating the heat insulating material 30 while scanning the infrared ray I in the plane direction to confirm the welding state is repeated while changing the conditions. Then, the side of the first molded body 10 in contact with the heat radiating material 30 that is irradiated with infrared rays I, that is, the side of the second surface 10b of the first molded body 10 is not burnt or deformed, and the first molded body 10 and the second molded body 10 are molded. _{The minimum value v 1} of the feed rate v to which the body 20 is welded and the minimum photon density P _{1 at that time, and the maximum value v 2} of the feed rate v and the maximum photon density P _{2 at} that time are obtained.

Here, "the side of the thermoplastic resin molded body to be irradiated with infrared rays (the second surface 10b side of the first molded body 10) is not burnt or deformed" means that the second surface 10b of the first molded body 10 ( It means that the appearance and shape of the outermost surface) have not changed since before welding.

"The thermoplastic resin molded bodies (the first molded body 10 and the second molded body 20) can be welded to each other" means that the welding strength between the thermoplastic resin molded bodies after welding is the first molded body 10 and the second molded body. It means that it is equal to or more than the tensile strength of each unit of the body 20 (N / 16 mm). However, depending on the purpose of use of the welded product, it may be possible to use the first molded product 10 and the second molded product 20 even if they have a tensile strength or less.
After welding the thermoplastic resin molded bodies together, a test piece having a width of 16 mm was cut out, and a tensile tester was used to use the welded portion of the test piece as a fulcrum under the conditions of a distance between chucks of 30 mm, a tensile speed of 10 mm / min, and a tensile direction of 90 °. A peeling method is adopted in which the maximum load until breakage when pulled to is the welding strength.

In the present embodiment, the following tests are first performed in advance.
_{The minimum value v 1} of the feeding speed v of the infrared ray I in the range where the first molded body 10 and the second molded body 20 can be welded without causing burning and deformation on the second surface 10b side of the first molded body 10. obtaining a minimum photon density P ₁ at a feed rate v _1. For example, a test is conducted in which the feed rate v of the infrared ray I is fixed and the photon density P is changed at an ^{interval of 4.823 × 10 22} feet / mm ² · s to confirm welding and deformation, and to measure the welding strength. From the result, the minimum photon density P capable of welding the first molded body 10 and the second molded body 20 without causing burning and deformation on the second surface 10b side of the first molded body 10 is obtained. _{This is repeated by changing the feed rate v at intervals of 10 mm / s, and the minimum value v 1} and the minimum photon density P ₁ of the feed rate v of the infrared ray I that can weld the molded bodies to each other without causing burning and deformation of the outermost surface. Ask for.
v ₁ and variation interval of photon density P in tests to determine the _{P 1} is not limited to ^{4.823 × 10 22 photons / mm 2} · s, for ^{example, 1.206 × 10 22 ~2.412 × 10} 23 It can be photons / mm ^{2 · s.} Further, the fluctuation interval of the feed rate v is not limited to 10 mm / s, and can be, for example, 1 to 356 mm / s.

_{Further, the maximum value v 2} of the feeding speed v of the infrared ray I in the range in which the first molded body 10 and the second molded body 20 can be welded without causing burning or deformation on the second surface 10b side of the first molded body 10. And the maximum photon density P ₂ when the feed rate v ₂ is measured. For example, a test is conducted in which the feed rate v of the infrared ray I is fixed and the photon density P is changed at an ^{interval of 4.823 × 10 22} feet / mm ² · s to confirm welding and deformation, and to measure the welding strength. From the result, the maximum photon density P capable of welding the first molded body 10 and the second molded body 20 without causing burning and deformation on the second surface 10b side of the first molded body 10 is obtained. _{This is repeated by changing the feed rate v at 10 mm / s intervals, and the maximum value v 2} of the feed rate v and the maximum photon density P _{2 of the} infrared ray I that can weld the molded bodies to each other without causing burning or deformation on the outermost surface. Ask for.
v ₂ and variation interval of the photon density P in tests to determine the _{P 2} is not limited to ^{4.823 × 10 22 photons / mm 2} · s, for ^{example, 1.206 × 10 22 ~2.412 × 10} 23 It can be photons / mm ^{2 · s.} Further, the fluctuation interval of the feed rate v is not limited to 10 mm / s, and can be, for example, 1 to 356 mm / s.

_{In the step (a), the minimum value v 1} of the feed rate, the minimum photon density P _1, and the maximum value v of the feed rate are selected by selecting the conditions using the prediction of the temperature rise due to infrared absorption described below. ₂ and the maximum photon density P ₂ can be efficiently obtained.
The temperature rise of the thermoplastic resin molded product due to the irradiation of infrared rays is proportional to the amount of infrared rays absorbed. The amount of infrared rays absorbed correlates with the intensity of the incident infrared rays and the extinction coefficient of the substance constituting the thermoplastic resin molded product, and follows Lambert-Beer's law. The amount of infrared rays absorbed is the largest on the surface where infrared rays are incident, and decreases as it goes inside.

The rate of temperature rise inside the molded product when irradiated with infrared rays can be approximately calculated from the following equations (1) and (2).

However, in the above formula, T is the temperature of the portion of the distance x from the surface of the molded body irradiated with infrared rays, t is the irradiation time of infrared rays, and x is the distance from the surface of the molded body irradiated with infrared rays. , K is the thermal conductivity of the molded body, ρ is the density of the molded body, c is the specific heat of the molded body, l ₀ is the intensity of the irradiated infrared rays, and β is the absorption of the molded body. It is a coefficient.

(Step (b))
As shown in FIG. 2, points A (v ₁ , P ₁ ) and points B (v ₂ , P ₂ ) are plotted on a graph showing the relationship between the feed rate v and the photon density P. Then, a straight line passing through these two points A and B is defined as a straight line k.

(Step (c))
In the graph of FIG. 2, among the points where the first molded body 10 and the second molded body 20 were not welded in the test, the points C (v _{3) below the straight line k and closest to the straight line k.} , P ₃ ) (where v ₃ > v ₂ ), the straight line k is moved in parallel, and the straight line p is defined as the straight line p.

(Step (d))
In the graph of FIG. 2, among the points where at least a part of the first molded body 10 and the second molded body 20 was whitened in the test, the point D (v) above the straight line k and closest to the straight line k. ₄ , P ₄ ) (where v ₄ <v ₁ ), the straight line k is moved in parallel, and the straight line q is defined as the straight line q.

In the present embodiment, when the first molded body 10 and the second molded body 20 are welded, they are above the straight line p and below the straight line q in the graph showing the relationship between the feed rate v and the photon density P. Within the range, the feed rate and photon density of the infrared ray I to be irradiated are controlled. As a result, the conditions can be easily set, and the first molded body 10 and the second molded body 20 can be continuously welded with high productivity and energy saving while suppressing thermal damage such as surface burning.

In the present embodiment, the feeding speed and photon density of infrared rays I irradiated on the straight line k within a range in which bubbles, whitening and blackening do not occur in the first molded body 10 and the second molded body 20 in the test are controlled. Is preferable.

Specifically, on the straight line k, the first molded body 10 and the second molded body 20 are formed in the first molded body 10 and the second molded body 20 without causing bubbles, whitening, and blackening in the test. _{The maximum value v 5} of the feed rate v that can be welded is obtained.
It should be noted that "no bubbles are generated in the thermoplastic resin molded body" cannot be confirmed with a 5x magnifying glass, and when confirmed with a 200x microscope, there is one or less bubbles with a diameter of 50 μm or more in ^{1 cm 3.} Means that The diameter of the bubble means the diameter of the circumscribed circle that circumscribes the bubble in the enlarged image.

_{As shown in FIG. 3, the point E (v 5} , P ₅ ) is plotted on the straight line k of the graph showing the relationship between the feed rate v and the photon density P. Then, in the range above the straight line p and below the straight line q in the graph of FIG. 3, in the range of the point B side (v ≧ v ₅ ) of the point E, the first molded body 10 and the second molded body 10 and the second molded body are formed. It is preferable to control the feeding speed and photon density of the infrared ray I irradiating the body 20.

In addition, when this case is the feed rate of the infrared I emitted from the light source 110 is v ₃ or more, a notification unit 120 first molded body 10 with a welding apparatus 100 having the in which it is notified second It is preferable to weld the molded body 20. This makes it easy to obtain a high-quality welded product without bubbles.

The notification means 120, as long as it can notify the feeding speed of the infrared I is v ₅ or more, for example, can be exemplified buzzer, the revolving lamp or the like.

In the present invention, the feeding speed of the infrared ray I to be irradiated is preferably 300 mm / s or more from the viewpoint that the welded product can be continuously produced with particularly excellent productivity.

The light source 110 can be appropriately selected in consideration of the type of the thermoplastic resin used for the first molded body 10 and the second molded body 20, the welding temperature, and the type of the heat radiating material 30.
As the light source 110, a light source capable of generating infrared rays having a wavelength capable of heating the welded portions of the first molded body 10 and the second molded body 20 to the melting temperature with sufficient output may be selected. For example, the light source 110 may have a wavelength of 0. A light source that generates infrared rays of 7. μm or more and 1,000 μm or less can be adopted.

As the light source 110, for example, an infrared laser is used.
Examples of the infrared laser include a solid-state laser, a semiconductor laser, a gas laser, a fiber laser, and a dye laser that generate infrared rays having a wavelength of 0.7 μm or more.

As the solid-state laser, an Nd-doped YAG laser (hereinafter, referred to as “Nd: YAG laser”) having a light source wavelength in the range of 0.94 μm or more and 1.4 μm or less can be exemplified. As the semiconductor laser, an AlGaAs laser having a light source wavelength in the range of 0.8 μm or more and 0.96 μm or less can be exemplified. Since some Nd: YAG lasers and semiconductor lasers have a high average output, they can be applied to welding a wide range of infrared-absorbing thermoplastic resin molded products.

A fiber laser (hereinafter referred to as "Ho, Er, Tm: fiber laser") having a wavelength of a light source doped with Ho, Er, or Tm (thulium) of 1.9 μm or more and 2.94 μm or less, or a light source that is a gas laser. _{A carbon dioxide gas laser (CO 2} laser) having a wavelength of 9.1 μm or more and 10.9 μm or less, preferably 9.3 μm or more and 10.6 μm or less, can be used as a resin having extremely high visible light transmission such as polycarbonate, polystyrene, and acrylic resin. On the other hand, it has a heating effect and is therefore preferably used. In particular, the CO ₂ laser is suitable as an infrared light source because it has a strong heating action on all thermoplastic resins and can increase the average output of the oscillator from several watts to several tens of kW.

An optical mirror, fiber, lens, mask, or the like may be used for transmission and irradiation of infrared rays I generated from the light source 110.

The thermoplastic resin constituting the first molded body 10 and the second molded body 20 is not particularly limited as long as it has infrared absorption. Specifically, polyolefins (polyethylene, polypropylene, polybutene, poly-4-methyl-1-pentene, ethylene-cyclic olefin copolymers, etc.), polyesters (ethylene-vinyl acetate copolymers and saponified products thereof, ethylene-acrylics, etc.) Acid copolymers, ethylene polyethylene terephthalates, polybutylene terephthalates, polyethylene naphthalates, etc.), polyamides (nylon 9T, nylon 6, nylon 66, nylon 46, nylon 12, MXD nylon, etc.), acrylic polymers (polymethylmethacrylate, etc.) , Polyacrylic acid, etc.), Polystyrene, Polyacrylonitrile, Acrylonitrile-butadiene-styrene copolymer, Halogen-containing polymer (vinyl chloride, polyvinylidene chloride, polyfluoroethylene, etc.), synthetic rubber (polybutadiene, polyisoprene, etc.) and their Examples thereof include hydrogenated products, thermoplastic elastomers (styrene-butadiene-styrene block copolymers, etc.) and their hydrogenated products, liquid crystal polymers, polyurethanes, polycarbonates, polysulfones, and polyether ether ketones.

The thermoplastic resin constituting the first molded body 10 and the second molded body 20 may be of one type or two or more types. The thermoplastic resin constituting the first molded body 10 and the second molded body 20 may be the same type of resin or different types of resin.
Although the first molded body 10 and the second molded body 20 have infrared absorption, a certain degree of infrared transmission is required because an effective amount of infrared rays must reach the welded surface.

The infrared absorption coefficient can be adjusted by uniformly containing the infrared absorber in the first molded body 10 and the second molded body 20. When either one or both of the first molded body 10 and the second molded body 20 contains an infrared absorber, it is preferable to select a welding condition in which the infrared absorber absorbs infrared rays and generates heat.
From the viewpoint of transparency, hygiene, and strength, it is preferable that the first molded product 10 and the second molded product 20 do not contain an infrared absorber.

One or both of the first molded body 10 and the second molded body 20 may contain a dye or a pigment in a part or all of the molded body for the purpose of improving the appearance and design. The total content of the dye and the pigment in the molded product is preferably 5% by mass or less, more preferably 3% by mass or less, and further preferably 2% by mass or less.

The first molded body 10 and the second molded body 20 of this example are in the form of a film. The first molded body 10 and the second molded body 20 may have a single-layer structure or a multi-layer structure. The shapes of the first molded body 10 and the second molded body 20 are not limited to the shapes of this example, and may be complicated shapes such as a sheet shape, a tubular shape, a tube shape, and a partial sphere. ..

The thickness of the first molded body 10 and the second molded body 20 is not particularly limited. From the viewpoint of welding efficiency and productivity, the thickness of the infrared-irradiated portion of the first molded product 10 can be, for example, 1 μm or more and 10 mm or less, and preferably 10 μm or more and 1 mm or less.

The molding method for producing the first molded body 10 and the second molded body 20 is not particularly limited, and for example, an injection molding method, a blow molding method, a tube molding method, a deformed extrusion molding method, a foam molding method, and compression molding. Examples thereof include a method, a calendar molding method, an extrusion molding method, and a cast molding method.
When the first molded body 10 and the second molded body 20 have a multi-layer structure, for example, extrusion laminating, dry laminating, or the like can be adopted.

As the heat radiating material 30, an infrared-transparent solid material is preferable. The heat radiating material 30 plays a role of suppressing overheating of the surface layer on the second surface 10b side of the first molded body 10 and suppressing thermal damage by a heat sinking action that efficiently absorbs a part of the heat generated by infrared absorption.

It is preferable that the solid heat radiating material 30 has a property that it is less likely to be damaged such as melting or cracking due to thermal shock during infrared irradiation, and can easily remove heat even after repeated use and has a low heat storage property. .. Therefore, it is preferable that the heat radiating material 30 has high transparency to the infrared rays to be irradiated, and further has high thermal conductivity, mechanical strength and heat resistance.

The thermal conductivity of the heat radiating material 30 is preferably 1 W / m · ° C. or higher, more preferably 10 W / m · ° C. or higher.
The thickness of the heat radiating material 30 is preferably 10 μm or more and 100 mm or less, and more preferably 100 μm or more and 100 mm or less.

As the material of the heat radiating material 30, a material that transmits infrared rays may be selected according to the light source used. For example, in the case of a semiconductor laser, Nd: YAG laser, Ho, Er, or Tm: fiber laser, alumina (thermal conductivity: 36 W / m · ° C), beryllia (thermal conductivity: 270 W / m · ° C), magnesia ( Examples thereof include thermal conductivity: 48 W / m · ° C.), quartz (thermal conductivity: 1-10 W / m · ° C.), and diamond (thermal conductivity: 2000 W / m · ° C.). Alumina, beryllium, magnesia, and diamond are preferable in terms of excellent thermal conductivity and more efficient heat removal.

When the light source is a carbon dioxide gas laser, the materials of the heat radiating material 30 are zinc selenium (thermal conductivity: 19 W / m · ° C.), zinc sulfide (thermal conductivity: 27 W / m · ° C.), and silicon (thermal conductivity: 27 W / m · ° C.). : 150 W / m · ° C.), gallium arsenide (thermal conductivity: 54 W / m · ° C.), diamond (thermal conductivity: 2000 W / m · ° C.) can be exemplified.

The material of the heat radiating material 30 is not limited to the above-mentioned materials, but other infrared crystal materials or other infrared crystal materials, as long as they have the property of transmitting infrared rays to be used, preferably further thermal conductivity, mechanical strength and heat resistance. Infrared glass material may be used. The "infrared crystalline material" means a crystalline inorganic material that transmits infrared rays. The "infrared glass material" means an amorphous inorganic material that transmits infrared rays.

Infrared crystal materials include zinc selenium (ZnSe), zinc sulfide (ZnS), silicon (Si), germanium (Ge), sapphire (Al ₂ O ₃ ), gallium arsenide (GaAs) and magnesia (MgO), and foot. Examples thereof include magnesium sulfide (MgF ₂ ) and calcium fluoride (CaF _2).
Infrared glass materials include quartz-based glass materials containing quartz as the main component, germanate-based glass materials containing germania as the main component, and oxide-based glass materials containing aluminate-based glass materials containing alumina as the main component. , A sulfide-based glass material, and a chalcogenide glass material can be exemplified.

The form of the welded product produced by using the welding method of the present invention is not particularly limited, and examples thereof include a bag, a box, a tube, and a cylinder. As a specific example of the welded material, for example, a bag-shaped container in which the peripheral portions of two thermoplastic resin films are welded to each other can be exemplified. Such a bag-shaped container can be applied to, for example, an infusion bag or the like.

As described above, in the present embodiment, the line above and above the straight line p in the graph showing the relationship between the feed rate v and the photon density P obtained by performing the steps (a) to (d) in advance. Within the range below q, the feed rate and photon density of infrared rays I irradiated during welding of the first molded body 10 and the second molded body 20 are controlled. This facilitates the setting of conditions, and continuously welds the first molded body 10 and the second molded body 20 with high productivity and energy saving while suppressing thermal damage such as burning and deformation of the outermost surface. Can be done.

The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in the present invention, the thermoplastic resin molded product to be welded is not limited to two as in the above-described embodiment, and three or more thermoplastic resin molded products can be welded.

For example, a support may be contact-arranged on the opposite side of the first molded body 10 of the second molded body 20 for the purpose of protecting the second surface 20b on the opposite side of the first surface 20a of the second molded body 20. ..
The form of the support may be appropriately selected according to the shape of the second molded body 20. The material of the support is not particularly limited, and examples thereof include metals such as steel, aluminum alloys, and copper alloys, silicon rubber, and combinations thereof.

As shown in FIG. 4, the method for welding the thermoplastic resin molded product of the present invention is a cylindrical infrared-absorbing first thermoplastic resin molded product 40 (hereinafter, referred to as “first molded product 40”). And a second thermoplastic resin molded body 50 having a cylindrical shape and absorbing infrared rays (hereinafter, referred to as “second molded body 50”) may be welded. In this case, an aspect in which infrared rays I are irradiated from the fixed light source 110 toward the first molded body 40 and the second molded body 50, and the infrared rays I are scanned by rotating the first molded body 40 and the second molded body 50. Is preferable.

In the present invention, a liquid may be used as the heat radiating material. As the liquid heat radiating material, water is preferable from the viewpoint of heat radiating property and cost. In this case, the thermoplastic resin molded product is preferably a molded product using a thermoplastic resin having low water absorption.

It is possible to replace the components in the embodiment with well-known components as appropriate without departing from the spirit of the present invention, and the above-mentioned modifications may be appropriately combined.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to the following description.

[Evaluation of welding strength]
A test piece with a width of 16 mm is cut out from the welded material, and the test piece is pulled with the welded part as a fulcrum under peeling conditions of a chuck distance of 30 mm, a tensile speed of 10 mm / min, and a tensile direction of 90 ° using a tensile tester to break the test piece. The maximum load up to that point was defined as the welding strength.

[Evaluation of burning and deformation]
The appearance of the outermost surface of the welded material irradiated with infrared rays was visually confirmed to determine the presence or absence of burning, and the outermost surface was touched with a finger to determine the presence or absence of deformation.

[Evaluation of bubbles, whitening, and blackening]
When the welded material was viewed with a 5x magnifying glass, no bubbles could be confirmed, and when the number of bubbles with a diameter of 50 μm in ^{1 cm 3 was 1 or less with a 200x microscope, it was judged that no bubbles were generated.}
In addition, the welded material was visually confirmed to determine the presence or absence of whitening and blackening.

[Example 1]
_{In the embodiment illustrated in FIG. 1, points A (v 1} , P ₁ ) and points B (v ₂ , P ₂ ) in the welding of the first molded body 10 and the second molded body 20 using the heat radiating material 30 are obtained. rice field.
As the first molded body 10, a nylon resin film (manufactured by Kuraray Co., Ltd., thickness 50 μm) was prepared. As the second molded body 20, a nylon resin film (manufactured by Kuraray Co., Ltd., thickness 500 μm) was prepared. A Ge plate (thickness 4 mm) was prepared as the heat radiating material 30. _{A CO 2} laser was used as the light source 110.
The heat radiating material 30 was contact-arranged on the second surface 10b of the first molded article 10 of the test body in which the first molded article 10 and the second molded article 20 were arranged in contact with each other. In a test to confirm the welding state by irradiating infrared rays I from the heat radiating material 30 side while scanning, the fluctuation interval of the photon density P was 4.823 × 10 ²² feet / mm ² · s, and the fluctuation interval of the feed rate v was 10 mm. _{The points A (v 1} , P ₁ ) and the points B (v ₂ , P ₂ ) were obtained by repeating the process while changing the conditions as / s. v ₁ is 87.4 mm / s, P ₁ is 2.19 × 10 ²¹ photons / mm ² · s, maximum value v ₂ is 154.2 mm / s, P ₂ is 5.31 × 10 ²¹ photos / mm ² ·. It was s.

Points A and B were plotted on a graph showing the relationship between the feed rate v and the photon density P, and the straight line passing through them was defined as a straight line k. In the graph, among the points where the first molded body 10 and the second molded body 20 were not welded in the test, the points below the straight line k and the closest to the straight line k are the points C (v ₃ , P). ₃ ), and the straight line obtained by translating the straight line k was defined as the straight line p. v ₃ was 168.0 mm / s, and P ₃ was 5.31 × 10 ²¹ photos / mm ² · s. Further, among the points where at least a part of the first molded body 10 and the second molded body 20 are whitened in the test, the point above the straight line k and the closest to the straight line k is the point D (v ₄ , and P _4), the straight line is moved parallel to the straight line k was linear q. v ₄ was 46.8 mm / s and P ₄ was 1.33 × 10 ²¹ photos / mm ² · s.

Next, on the straight line k, the feed rate v capable of welding the first molded body 10 and the second molded body 20 without causing bubbles, whitening and blackening in the first molded body 10 and the second molded body 20. The maximum value v ₅ was calculated. v ₅ was 136.9 mm / s and P ₅ was 4.37 × 10 ²¹ photos / mm ² · s.

10, 40 ... Infrared-absorbing first thermoplastic resin molded product, 20, 50 ... Infrared-absorbing second thermoplastic resin molded product, 30 ... Heat-dissipating material, 100 ... Welding device, 110 ... Light source, 120 ... Notification means.

Claims (3)

At least two infrared-absorbing thermoplastic resin molded bodies are placed in contact with each other, and a heat-dissipating material is placed in contact with the outer surface of the outer surface of the thermoplastic resin molded body on one side, and infrared rays are scanned from the heat-dissipating material side. It is a method of welding the thermoplastic resin molded bodies to each other by irradiating while irradiating.
The feed rate of the infrared rays to be scanned is v (mm / s), and the photon density of the infrared rays is P (photons / mm ² · s). A thermoplastic resin molded body that controls the infrared ray feeding rate and photon density to be irradiated within the range above the straight line p and below the straight line q in the graph showing the relationship between the velocity v and the photon density P. Welding method.
Step (a): The heat-dissipating material is contact-arranged on the outer surface of the thermoplastic resin molded body on the outer side of one of the test pieces in which the thermoplastic resin molded bodies to be welded are arranged in contact with each other, and the heat-dissipating material side. The test of irradiating the thermoplastic resin molded body while scanning the infrared rays to confirm the welding state was repeated while changing the conditions, and the thermoplastic resin molded body in contact with the heat radiating material was not burnt or deformed on the side to be irradiated with the infrared rays. _{The minimum value v 1} of the feed rate v at which the thermoplastic resin molded bodies are welded to each other and the minimum photon density P _{1 at that time, and the maximum value v 2} of the feed rate v and the maximum photon density P _{2 at} that time are set. Ask.
Step (b): Point A (v ₁ , P ₁ ) and point B (v ₂ , P ₂ ) are plotted on a graph showing the relationship between the feed rate v and the photon density P, and a straight line passing through the points A and B. Let be a straight line k.
Step (c): Among the point at which the thermoplastic resin molded article in the test of the graph has not been welded, the below side of the straight line k, and most distance point close C to the straight line k (v _3, Let the straight line p be a straight line obtained by moving the straight line k in parallel to P ₃ ) (where v ₃ > v _2).
Step (d): Of the points where the thermoplastic resin molded product was whitened in the test in the graph, points D (v ₄ , P ₄ ) above the straight line k and closest to the straight line k. (However, the straight line obtained by moving the straight line k in parallel up to _{v 4} <v _{1) is defined as the straight line q. On the straight line k, the maximum value v 5} of the feed rate v capable of welding the thermoplastic resin molded bodies to each other without causing bubbles, whitening and blackening in the thermoplastic resin molded body was obtained in the test. The method for welding a thermoplastic resin molded product according to claim 1, wherein the feed rate and photon density of the infrared rays irradiated in the range where the feed rate v is v ₁ or more and v _{5 or less are controlled.} Welding the said thermoplastic resin molded bodies using a welding apparatus provided with a notifying means for notifying it when the feed speed of the infrared is v ₅ or more, the thermoplastic resin molded article according to claim 2 Welding method.

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