JP2011126237A - Laser welding method of resin material and welding resin molded article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser welding method capable of obtaining at high efficacy a molded article having high quality where welding strength is stable and there is no extrusion, dull nor the deforming of the article even if there is a clearance partially and to provide a welding resin molded article obtained by the method. <P>SOLUTION: In a laser welding method for welding a permeable resin material (A) making a laser ray permeate with a non-permeable resin material (B) making a laser ray not permeate by irradiation with laser rays, a spot diameter of the laser ray irradiating an welding surface is changed according to a size of a clearance formed at the welding surface of the permeable resin material (A) and the non-permeable resin material (B), and laser ray irradiation energy (J/mm<SP>2</SP>) per unit surface area in the welding part is kept around one and the same value. A welding resin molded article is obtained by the method. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a resin member laser welding method and a welded resin molded product, and more specifically, has a stable welding strength and a protruding portion of a welded portion even if there is a gap between resin members to be welded. The present invention relates to a laser welding method of a resin member that can efficiently obtain a high-quality welded molded product free from dullness and deformation of the molded product, and a welded resin molded product obtained by the method.

Conventionally, a transparent material having a large laser light transmittance and an absorptive material having a small laser light transmittance are overlapped, and the contact surface of both materials is irradiated with laser light from the outside of the transparent material. A plastic welding method for welding is generally known.
Since laser welding is a welding method with less sinking, in order to obtain a stable welding state, the contact surface between the permeable material and the absorbent material needs to be brought into close contact and welded in this state. Therefore, conventionally, a method is adopted in which a large force is applied to the contact surface from the outside in a state where the permeable material and the absorbent material are in contact with each other, and the contact surface is improved by this applied pressure.

  In the conventional plastic welding method, since the method of ensuring the close contact of the contact surface only by the pressure from the outside, the pressurizing means is complicated, the size is increased, the cost is increased, and the handling is not easy, In addition, even when a large external force is applied, the contact surface cannot always be secured, and there is a problem in that if there is a gap in the contact surface, the welding strength decreases, and a stable welding strength cannot be obtained. That is, air is interposed in the gap portion, and the thermal conductivity is deteriorated, so that the resin is decomposed and the like, and the welding strength is reduced due to foaming.

  As a means for solving such a problem, that is, as a means for suppressing a decrease in welding strength even if there is a gap in the contact surface, a method of preheating the contact surface has been proposed (for example, Patent Document 1, Patent Document 2, (See Patent Document 3.)

In the laser welding method of the resin material described in Patent Document 1, the surface of the transparent resin material that comes into contact with the absorbent resin material before the transparent resin material and the absorbent resin material are welded by welding laser light. And the surface of the absorptive resin material which contacts the permeable resin material is preheated and softened. Accordingly, in the laser welding method of the resin material described in the same document, when the close contact between the surface of the transparent resin material and the surface of the absorbent resin material is poor, that is, the surface of the transparent resin material and the absorbent resin Even when unevenness exists on the surface of the material, the welding strength between the permeable resin material and the absorbent resin material is improved.
Specifically, this document describes electromagnetic induction as a method for preheating the surface of the permeable resin material that contacts the absorbent resin material and the surface of the absorbent resin material that contacts the permeable resin material. A heating method, a heater heating method, a hot air heating method, an infrared lamp heating method, and a laser heating method are described.

Moreover, in the laser welding method of the resin material described in patent document 2, before the permeable resin material and the non-permeable resin material are welded by the welding laser beam, the permeability which contacts the non-permeable resin material is used. The surface of the resin material and the surface of the non-permeable resin material in contact with the permeable resin material are preheated and softened. Thereby, in the laser welding method of the resin material described in Patent Document 2, when the close contact between the surface of the permeable resin material and the surface of the non-permeable resin material is poor, that is, the surface of the permeable resin material Even if there are irregularities on the surface of the permeable resin material, the welding strength between the permeable resin material and the absorbent resin material is improved.
Specifically, in Patent Document 2, as a means for preheating the surface of the permeable resin material that contacts the non-permeable resin material and the surface of the non-permeable resin material that contacts the permeable resin material. A preheating laser beam, a heating member and hot air are described.

Furthermore, in the laser welding method of the resin material described in Patent Document 3, the first resin member having a high laser beam transmittance and the second resin member having a low laser beam transmittance are welded by the welding laser beam. Before, the contact surface of the first resin member and the second resin member is preheated and softened. Thereby, in the laser welding method of the resin material described in Patent Document 3, the adhesion between the surface of the first resin member having a high laser light transmittance and the surface of the second resin member having a low laser light transmittance is low. Even if there are irregularities on the surface of the first resin member having a high laser light transmittance and the surface of the second resin member having a low laser light transmittance, the laser light transmittance is high. The welding strength between the first resin member and the second resin member having a low laser beam transmittance is improved.
Specifically, Patent Document 3 discloses a method for preheating a contact surface between a first resin member having a high laser light transmittance and a second resin member having a low laser light transmittance by welding laser light. As a means, a preheating laser beam having a spot diameter larger than the spot diameter of the welding laser beam is described.

  In these preheating methods, the entire contact surface is basically heated regardless of the presence or absence of a gap, so that there are problems such as dull appearance, deformation of the product due to insufficient heat resistance and strain relaxation. . Similarly, if the laser output is increased to obtain a stable adhesive strength in the gap portion, defects such as burning or melting may occur on the surface of the laser light transmitting resin member, or the molten or expanded resin member may protrude. The appearance of the product may be impaired and the quality may be deteriorated.

  Therefore, as a laser welding method of the resin member, there is no protrusion of the welded portion, dullness or deformation of the molded product, and even if there is a partial gap between the resin members to be welded without impairing the appearance of the product, it is sufficient. There has been a demand for a simple method capable of irradiating a laser beam without excess or deficiency to obtain a welding strength and obtaining a high-quality molded product.

JP 2004-74734 A JP 2004-188802 A JP 2007-182003 A

  The object of the present invention is to solve the problems of the prior art described above, even if there is a gap between the resin members to be welded, even if there is a gap, it has a stable welding strength, and the protrusion of the welded part and the dullness of the molded product Another object of the present invention is to provide a resin member laser welding method capable of efficiently obtaining a high-quality welded molded product free from deformation and a welded resin molded product obtained by the method.

As a result of intensive studies to solve the above problems, the present inventors have found that when a transparent resin member that transmits laser light and a non-transparent resin member that does not transmit laser light are welded together, Depending on the size of the gap generated on the contact surface of the member, the spot diameter of the laser beam irradiated on the contact surface is changed, and the laser beam irradiation energy per unit area on the contact surface (J / mm ² ) Was found to be able to solve the above problems. These findings have been further studied and the present invention has been completed.

That is, according to the first aspect of the present invention, laser welding is performed by welding a transparent resin member (A) that transmits laser light by irradiation with laser light and an impermeable resin member (B) that does not transmit laser light. In the method
According to the size of the gap between the two members generated on the contact surface between the transparent resin member (A) and the non-transparent resin member (B), the spot diameter of the laser light applied to the contact surface is changed, and There is provided a method of laser welding a resin member, characterized in that the laser beam irradiation energy (J / mm ² ) per unit area on the contact surface is kept substantially the same.

  According to the second invention of the present invention, in the first invention, the spot diameter of the laser beam is generated on the contact surface between the transmissive resin member (A) and the non-transmissive resin member (B). There is provided a laser welding method for a resin member, characterized in that the larger the gap (distance) between the two members is, the larger the gap is.

According to a third aspect of the present invention, there is provided the method for laser welding a resin member according to the first or second aspect, wherein the spot diameter of the laser beam satisfies the following relationship.
A _d ≧ 0.012d + 1.8 Formula (1)
(In the formula, _Ad is the spot diameter [mm] of the laser beam on the contact surface when the gap distance between the transparent resin member and the non-permeable resin member is d, and d is the transparent resin member and the non-permeable material. (Gap distance [mm] with resin member)

  According to a fourth invention of the present invention, in any one of the first to third inventions, the laser beam irradiation energy per unit area on the contact surface is the laser beam irradiation output (W) and / or There is provided a laser welding method for a resin member, characterized in that it is kept substantially the same by changing the scanning speed (mm / sec) of laser light.

  According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the spot diameter of the laser light is adjusted by adjusting a distance between the laser light source and the corresponding contact surface. A laser welding method is provided which is characterized by being varied.

  According to a sixth aspect of the present invention, in any one of the first to fourth aspects, the spot diameter of the laser light is changed by adjusting a focal length of the laser light. A laser welding method is provided.

  According to a seventh invention of the present invention, in any one of the first to fourth inventions, the spot diameter of the laser light is an adjustment of an irradiation angle between the optical axis of the laser light and the corresponding contact surface. There is provided a laser welding method characterized in that the laser welding method is changed.

  According to an eighth invention of the present invention, in any one of the first to seventh inventions, the permeable resin member (A) and the non-permeable resin member (B) are preliminarily formed prior to welding by the laser light irradiation. The method of laser welding a resin member is provided in which the size (distance) of the gap between the two members generated on the contact surface is detected.

  According to a ninth aspect of the present invention, in the eighth aspect, the size (distance) of the gap is detected by any one of an optical method, an electrical method, and a thermal method. A method for laser welding a resin member is provided.

  According to a tenth aspect of the present invention, in the eighth aspect of the invention, the size (distance) of the gap is detected on the contact surface by a permeable resin member (A) and a non-permeable resin member ( A resin member laser welding method is provided, which is performed by irradiating a laser beam for heating the member below the melting temperature of B) and monitoring the temperature of the contact surface at that time.

  According to the eleventh aspect of the present invention, in any one of the first to seventh aspects, the permeable resin member (A) and the non-permeable resin member (B) are preliminarily formed prior to welding by the laser light irradiation. ) And the permeable resin member (B ′) and the non-permeable resin member (B ′) respectively produced on the same production line. ) Is irradiated with a laser beam having a spot diameter determined according to the detection result, and the corresponding contact surface is welded. Thus, a resin member laser welding method is provided.

  According to the twelfth aspect of the present invention, there is provided a welded resin molded article obtained by the laser welding method for a resin member according to any one of the first to eleventh aspects.

  According to the laser welding method and resin molded product of the resin member of the present invention, in the first invention, irradiation is performed by changing the spot diameter of the laser beam according to the size of the gap between the two members generated on the contact surface. By increasing the amount of resin (volume) to be melted by heating and filling the gap, the welding strength of the part can be improved. There is an effect that a welded resin molded article having stable welding strength can be obtained without damaging.

  Further, in the second or third invention, in the contact surface, in the portion where there is a gap, by increasing the spot diameter of the laser light at a specific ratio according to the distance of the gap, The amount (volume) of resin melted by heating can be increased, and the gap can be reliably filled. Thereby, since the welding strength of the said site | part can be improved, even if there exists a clearance gap partially, there exists an effect that the welding resin molded product of the stable welding strength is obtained.

  In the fourth invention, the laser beam irradiation energy per unit area irradiated on the contact surface is determined by the irradiation output (W) of the laser beam and / or the scanning speed (mm / sec) of the laser beam. Since it is kept substantially the same by changing, it is possible to easily perform laser light irradiation that is adjusted without excess or deficiency, there is no occurrence of leakage due to insufficient welding in the gap, and the welding part protrudes, etc. There is an effect that it is possible to obtain a welded resin molded product having no high quality.

  In the fifth to seventh inventions, since the spot diameter of the laser beam is simply adjusted, there is an effect that the welding can be performed efficiently.

  In the eighth to tenth inventions, the size of the gap between the two members generated in advance on the contact surface between the transparent resin member (A) and the non-permeable resin member (B) prior to welding by laser light irradiation. Since the length (distance) is detected in detail, it is possible to perform laser light irradiation with adjusted excess and deficiency, there is no occurrence of leakage due to insufficient welding in the gap, and the welding part protrudes, etc. There is an effect that a high-quality welded resin molded product can be obtained.

  In the eleventh aspect of the invention, prior to welding by laser light irradiation, the size (distance) of the gap between both members generated on the contact surface between the transparent resin member and the non-permeable resin member is detected in advance. A laser beam having a spot diameter determined in accordance with this is applied to the contact surface between another transmissive resin member (A ′) and non-permeable resin member (B ′) manufactured on the same production line. In addition, since the corresponding contact surface is welded, there is no need to detect the gap distance for each laser irradiation of one member, and the same molded product can be repeatedly produced efficiently and at low cost. .

  Moreover, in the twelfth invention, since it is a welded resin molded product obtained by the first to eleventh methods, there is an effect that it is a high-quality molded product.

FIG. 1 is a schematic view showing an example of a method for changing the spot diameter of laser light on the contact surface by adjusting the distance between the laser light source and the contact surface in the present invention. FIG. 2 is a schematic view showing an example of a method of changing the spot diameter of laser light on the contact surface by adjusting the focal length in the present invention. FIG. 3 is a schematic view showing an example of a method of changing the spot diameter of the laser beam on the contact surface by adjusting the irradiation angle between the optical axis of the laser beam and the contact surface in the present invention. FIG. 4 is a schematic view showing an example of a member to be welded in the present invention. FIG. 5 is a graph showing an example in which a gap is detected by thermal means for the member of FIG. FIG. 6 is a graph showing an example in which the gap of the member of FIG. 4 is detected by thermal means and the spot diameter is increased using this result. FIG. 7 is a schematic view showing an example of a gap detection and welding laser arrangement in the present invention. FIG. 8 is a schematic view showing an example of a resin member used in the examples. FIG. 9 is a schematic view showing an example of the welding strength measuring method used in the example, and shows an XY cross-sectional view of FIG.

1 Laser Light Source 2 Laser Light 3 Translucent Resin Member (A)
4 Non-permeable resin member (B)
5 Abutting surface 6, 7, 8 Laser light irradiation part on abutting surface

Hereinafter, the laser welding method of the resin member of this invention is demonstrated in detail for every item.
The laser welding method of the resin member of the present invention is a laser welding method in which a transparent resin member (A) that transmits laser light by laser light irradiation and an impermeable resin member (B) that does not transmit laser light are welded. ,
According to the size of the gap between the two members generated on the contact surface between the transparent resin member (A) and the non-transparent resin member (B), the spot diameter of the laser light applied to the contact surface is changed, and The laser light irradiation energy (J / mm ² ) per unit area on the contact surface is kept substantially the same.

[Optical characteristics of each member]
In the present invention, when welding a transparent resin member that transmits laser light and a non-transparent resin member that does not transmit laser light, laser light is irradiated from the side of the transparent resin member that transmits laser light. Thus, the laser light passes through the transparent resin member having a high transmittance with respect to the laser light. The transmitted laser light reaches the surface of the non-transmissive resin member that does not transmit the laser light and is accumulated as energy. This accumulated energy distribution becomes a non-uniform energy distribution due to scattering during transmission of the transparent resin member with respect to the energy distribution previously possessed by the laser beam. Further, since heating and melting with non-uniform energy distribution are performed on the contact surface of the member, a joined portion in which the permeable resin member and the non-permeable resin member are intertwined with each other is generated and obtained. The joined portion of the joined body becomes strong.

At this time, if there is a gap between the permeable resin member and the non-permeable resin member that are in contact with each other, poor welding tends to occur. When there is a gap between the resin materials, the heat generated on the surface of the non-permeable resin member due to the absorption of the laser light is difficult to be transmitted to the surface of the opposing transparent resin member. For this reason, the surface temperature of a non-permeable resin member becomes high compared with the case where there is no gap. That is, when there is a gap between the resin materials, not only the welding strength is inferior, but the temperature of the surface of the laser light non-permeable resin member becomes too high, causing problems such as burning and gas generation, which impairs the appearance. There was a problem.
In the present invention, the spot diameter of the laser beam irradiated on the contact surface according to the size of the gap between the two members generated on the contact surface between the transparent resin member (A) and the non-permeable resin member (B). And the laser beam irradiation energy (J / mm ² ) per unit area on the abutting surface is kept substantially the same without causing adverse effects such as protrusion of the welded portion, dullness or deformation of the molded product. The resin around the gap is melted, and a high-quality welded molded product can be obtained with a stable welding strength.

  The laser light transmittance of the transparent resin member is preferably 30% or more. If the transmittance of the transparent resin member with respect to the laser beam is less than 30%, the laser beam is diffused in the portion that receives the laser beam, and the energy of the laser beam incident on the non-transparent resin member is reduced. Insufficient welding at the contact surface makes it difficult to obtain a desired welding strength. The preferable transmittance of the transparent resin member with respect to the laser light is 40% or more, and more preferably 50% or more.

On the other hand, it is not necessary for the non-transparent resin member to transmit laser light at all, and it is important that the non-transparent resin member be smaller than the laser light transmittance of the transparent resin member. Is preferably less than 30%. When the transmittance is 30% or more, the incident laser beam is transmitted, so that the energy of the laser beam absorbed by the non-transmissive resin member is reduced and the welding on the contact surface becomes insufficient. At the same time, energy loss of the laser beam is likely to occur. The preferable transmittance of the non-transmissive member with respect to the laser beam is 20% or less, and preferably 10% or less.
The non-transparent resin member preferably contains a laser light absorbing material in order to obtain a transmittance of less than 30% with respect to the laser light. As this laser light absorbing material, for example, inorganic colorants such as carbon black and complex oxide pigments, and organic colorants such as phthalocyanine pigments and polymethine pigments can be used, either alone or in combination. The above can be used in combination, but among these, carbon black is preferred from the viewpoints of effects and economy.

  In addition, the transmittance | permeability (%) with respect to the laser beam of a transparent resin member and a non-transmissive resin member is ASTM No. 1 dumbbell using a power energy analyzer (Fieldmaster (trademark registration) GSLM-45 by Coherent Japan Co., Ltd.). It is the value measured about what was shape | molded in this shape.

[Laser irradiation method]
In the method of the present invention, the laser beam is irradiated on the contact surface according to the size of the gap between the two members generated on the contact surface between the transparent resin member (A) and the non-permeable resin member (B). It is necessary to change the spot diameter of the laser beam irradiated to the laser beam and to keep the laser beam irradiation energy (J / mm ² ) per unit area on the contact surface substantially the same.
Without changing the spot diameter according to the size of the gap between the two members on the contact surface, if the laser passes through the same spot diameter without any gap, the weld will not be welded to the gap. Or heat is generated due to the heat insulation effect, foaming, burning, etc. occur, and the welding strength becomes extremely low. In addition, the spot diameter is changed according to the size of the gap between the two members generated on the contact surface. The light irradiation energy will increase or decrease. Thus, when laser beam irradiation energy is not kept substantially the same, excess and deficiency occurs in the irradiation energy, which also causes a problem that the welding strength decreases. In the present invention, in order to improve the above problems, the laser beam is defocused by a method such as changing the distance between the laser beam generation source and the resin member to be welded (also referred to as “work”), and a wide range of resins. Therefore, it is considered that the welding strength can be improved without any problem in appearance.

The determination of the presence or absence of a gap is not particularly limited, and can be performed by visual observation, an optical method, an electrical method, a thermal method, or the like. For example, when sink marks or warps occur in a member, laser light having a spot diameter changed to be larger than the spot diameter of laser light applied to a contact surface where there is no gap is used. Irradiate the contact surface of the part where the gap is generated due to the influence of the above. As described above, the spot diameter of the gap portion when sink marks, warps or the like are generated on the member is preferably about 1 to 10 mm, more preferably about 1.2 to 7 mm, and still more preferably 1.5. It can be set to about 4 mm.
As a result, even in a member having a gap due to sinking, warping, etc., the amount of resin (volume) to be heated and melted is increased in the portion where there is a gap, and the welding strength of the part is increased by filling the gap. Since it can be improved, a molded article having stable welding strength can be obtained.

  Further, the spot diameter of the laser beam on the abutting surface should be changed so as to increase as the size (distance) of the gap between both members generated on the abutting surface between the transmissive resin member and the non-permeable resin member increases. Is preferred.

  Preferably, the spot diameter of the laser beam on the contact surface satisfies the relationship of the following formula (1).

A _d ≧ 0.012d + A ₀ formula (1)
(In the formula, _Ad is the spot diameter [mm] of the laser beam on the contact surface when the distance between the transparent resin member and the non-permeable resin member is d, and d is the non-transparent resin member and the non-transmissive resin member The gap distance [μm] between the transparent resin member and A ₀ represents the spot diameter [mm] of the laser beam on the contact surface when the gap distance between the transparent resin member and the non-permeable resin member is zero. )

Here, the spot diameter A ₀ [mm] of the laser beam on the contact surface when the gap distance between the permeable resin member and the non-permeable resin member is 0 is required for the specification of the apparatus, the material of the member, and the like. It can be determined by appropriately adjusting according to the welding width, temperature, appearance and the like.
For example, the spot diameter of the normal portion 1.8 mm, d is 50 [[mu] m], the spot diameter _{A d} of the abutment surface is preferably set to 2.4 [mm] or more. If it is smaller than 2.4 [mm], stable welding strength may not be obtained.
According to the above formula (1), by adjusting the spot diameter according to the gap distance of the contact surface, it is possible to perform more adjusted laser light irradiation without excess or deficiency according to the state of the welded portion. In addition, it is possible to obtain a high-quality molded product that is free from protrusion of the welded portion and dullness or deformation of the molded product.

Note that the laser beam irradiation needs to be performed while keeping the laser beam irradiation energy (J / mm ² ) per unit area on the contact surface substantially the same.
Here, “substantially the same” means that the laser beam irradiation energy (J / mm ² ) per unit area irradiated on the contact surface of the portion where the gap exists is applied to the contact surface of the normal portion where there is no gap. It is to keep constant in comparison with the irradiation energy (J / mm ² ) of the laser beam per unit area, and thereby stable welding strength can be maintained. In other words, the laser beam irradiation energy (J / mm ² ) per unit area irradiated on the contact surface is kept constant at any point from the start point to the end point of the welding line. More specifically, the laser beam irradiation energy of the gap portion is preferably about ± 30%, more preferably, based on the laser beam irradiation energy of the normal portion where the contact surface is kept in close contact before and after the gap portion. It means about ± 20%, more preferably about ± 10%.
Therefore, when the laser beam irradiation energy (J / mm ² ) cannot be said to be substantially the same, it is possible to perform laser beam irradiation with no excess or deficiency according to the state of the welded part such as a gap partially formed. Therefore, there is a possibility that the welded portion protrudes and the molded product is dull, deformed or burnt, and a high-quality molded product cannot be obtained.
The laser beam irradiation energy (J / mm ² ) per unit area irradiated on the contact surface is a value obtained by measuring the irradiation energy using an optical power meter and dividing by the spot diameter. is there.

A method for performing laser light irradiation by changing the spot diameter of the laser light and maintaining the laser light irradiation energy (J / mm ² ) per unit area irradiated on the contact surface substantially the same is particularly limited. Although not performed, it is preferable to change the laser beam irradiation output (W) and / or the laser beam scanning speed (mm / sec). The irradiation time is adjusted by changing the scan speed.
For example, at a location where the spot diameter is increased without changing the scanning speed, the laser beam irradiation output is adjusted to be large, or at a location where the spot diameter is increased without changing the laser beam output. The scanning speed can be slowed down and the irradiation time can be lengthened. Specifically, in the normal welding process, the irradiation time is linearly welded while fixing the workpiece and moving the laser, or moving the workpiece while fixing the laser. The irradiation time can be adjusted by changing the speed. Further, both the laser beam irradiation output and the scanning speed can be changed.
As a result, laser light irradiation can be performed easily and without excess or deficiency without using a specific process or apparatus separately, and there is no occurrence of leakage due to insufficient welding in the gap portion, and the weld portion protrudes. It is possible to obtain a high-quality molded product without any such problems.

The method for changing the spot diameter of the laser beam on the contact surface is not particularly limited, but for example, it is preferable to change it as follows.
1. The distance is changed by adjusting the distance between the laser light source and the contact surface.
2. It is changed by adjusting the focal length of the laser beam.
3. It is changed by adjusting the irradiation angle between the optical axis of the laser beam and the contact surface.

FIG. 1 is a schematic view showing an example of a method for changing the spot diameter of laser light on the contact surface by adjusting the distance between the laser light source and the contact surface. In FIG. 1, the spot diameter is changed by changing the distance between the laser light source 1 and the workpiece contact surface 2. In FIG. 1A, the distance between the laser light source 1 and the work contact surface 5 is adjusted so that the spot diameter of the laser light irradiation unit 6 on the contact surface becomes as small as about 1.8 [mm]. It is used when the size (distance) of the gap between the two members formed on the contact surface between the permeable resin member and the non-permeable resin member is substantially zero. In FIG. 1B, the spot diameter of the laser light irradiation unit 7 on the contact surface is shortened by shortening the distance between the laser light source 1 and the contact surface 5 as compared with the case of FIG. This is adopted when there is a gap on the contact surface between the permeable resin member and the non-permeable resin member. Similarly, in FIG. 1C, as compared with the case of FIG. 1A, by increasing the distance between the laser light source 1 and the contact surface 5, the laser light irradiation unit 7 on the contact surface is obtained. This is adopted when the spot diameter is changed so as to increase, and there is a gap on the contact surface between the permeable resin member and the non-permeable resin member.
As described above, the method of changing the spot diameter of the laser beam on the contact surface by adjusting the distance between the laser light source and the contact surface is not particularly limited. For example, a six-axis robot apparatus is used. Height can be adjusted.

FIG. 2 is a schematic diagram showing an example of a method for changing the spot diameter of the laser beam on the contact surface by adjusting the focal length of the laser beam. In FIG. 2, the spot diameter is changed by changing the focal length of the laser beam 2. In FIG. 2A, the focal length of the laser beam 2 is adjusted so that the laser beam 2 is focused at the laser beam irradiation unit 6 on the contact surface. This is employed when the size (distance) of the gap between the two members generated on the contact surface is substantially zero. In FIG. 2B, compared with the case of FIG. 2A, by increasing the focal length of the laser beam 2, the spot diameter of the laser beam irradiation unit 7 on the contact surface is changed to be larger. This is employed when a gap is formed on the contact surface between the permeable resin member and the non-permeable resin member. Similarly, in FIG. 2C, the spot diameter of the laser beam irradiation unit 7 on the contact surface is increased by shortening the focal length of the laser beam 2 as compared with the case of FIG. This is adopted when there is a gap on the contact surface between the permeable resin member and the non-permeable resin member.
Such a method of changing the spot diameter of the laser beam on the contact surface by changing the focal length of the laser beam is not particularly limited, and examples thereof include a method of adjusting the curvature and refractive index of the lens.

FIG. 3 is a schematic diagram showing an example of a method for changing the spot diameter of the laser beam on the contact surface by adjusting the irradiation angle between the optical axis of the laser beam and the corresponding contact surface. In FIG. 3, the spot diameter is changed by changing the irradiation angle of the laser beam 2. In FIG. 3 (a), the irradiation angle of the laser beam 2 is adjusted so that the optical axis of the laser beam 2 and the contact surface 5 are substantially perpendicular to each other. This is employed when the size (distance) of the gap between the two members generated on the contact surface is substantially zero. In FIG. 3B, the spot diameter of the laser beam irradiation part 7 on the contact surface is increased by increasing or decreasing the irradiation angle of the laser beam 2 as compared with the case of FIG. This is adopted when there is a gap on the contact surface between the permeable resin member and the non-permeable resin member.
A method for changing the irradiation angle of the laser beam on the contact surface is not particularly limited. For example, the angle can be adjusted using a six-axis robot apparatus.

(Laser light)
In the present invention, the laser beam used for laser welding is glass: neodymium 3+ laser, YAG: neodymium 3+ laser, ruby laser, helium-neon laser, krypton laser, argon laser, H ₂ laser, N ₂ laser, semiconductor laser. And the like. A more preferable laser is a semiconductor laser.
The wavelength of the laser beam varies depending on the type of the resin member to be bonded and the type of the near-infrared absorber, and thus cannot be determined unconditionally, but is preferably 400 nm or more. If the wavelength is shorter than 400 nm, the resin member is likely to deteriorate significantly. A more preferable wavelength of the laser light is 400 to 1300 nm.
Further, the output of the laser beam can be adjusted by the scanning speed and the absorption capability of the transmissive resin member. When the output of the laser beam is low, it becomes difficult to melt the contact surfaces of the resin members, and when the output is high, problems such as evaporation of the resin member or deterioration of the resin member due to deterioration.

[Measurement of gap distance]
In the present invention, prior to welding by laser light irradiation, after detecting the size (distance) of the gap between both members generated on the contact surface between the transparent resin member and the non-permeable resin member in advance by temperature measurement or the like, It is preferable that the contact surface is welded by irradiating the contact surface with laser light having a spot diameter determined according to the detection result. Thereby, the adjusted laser beam irradiation without excess and deficiency can be performed, there is no occurrence of leakage due to insufficient welding in the gap portion, and a high-quality molded product without protrusion of the welded portion can be obtained.
According to the present invention, it is possible to weld even a gap with a gap distance of about 0 to 500 μm, preferably about 0 to 100 μm, more preferably about 0 to 50 μm.
The gap may be caused by a design such as embossing, or one or both of the joint surfaces may be caused by sinking or warping of the member.

  The method for measuring the gap distance is not particularly limited, and various known methods can be used, but any one of an optical method, an electric method, and a thermal method is preferable. Examples of the optical method include those using an infrared laser and other lasers, the electric method using electromagnetism, and the thermal method using temperature measurement.

In the present invention, the size (distance) of the gap between the two members generated on the contact surface is detected by a laser that heats the member to the contact surface below the melting temperature of the permeable resin member and the non-permeable resin member. It is preferable to carry out by irradiating light and monitoring the temperature of the corresponding contact surface at that time. Specifically, the line to be welded is scanned once or twice or more with a laser beam such as an output or a wavelength that heats the member below the melting temperature of the permeable resin member and the non-permeable resin member. At this time, since the resin temperature rises in the gap due to heat conduction, the gap can be detected by monitoring the temperature.
For example, FIG. 4 is a top view of a rectangular parallelepiped container having a pair of flanges so that the flange portions overlap each other, and is a portion where the flanges should be welded. The rib is provided in the back surface of the flange between a and b, and the clearance gap has arisen in contact part ab by the sink of a member. When one round on the line of A → B → C → D → A is a planned welding line, if there is a gap between a and b, the temperature rises at the gap (see FIG. 5). Therefore, the spot diameter of the laser beam used for welding at the portion where the temperature has increased may be made larger than the portion where no increase in temperature is observed, that is, the portion where no gap is formed.
As described above, if the gap can be detected, as shown in FIG. 6, it is preferable to increase the spot diameter from a short time before the laser passes through the portion to a point just past. Thereby, welding of a clearance gap part can be performed reliably.

  Further, in the present invention, the size (distance) of the gap between the two members generated on the contact surface between the transparent resin member (A) and the non-permeable resin member (B) in advance prior to welding by laser light irradiation. Spot detected on the contact surface of another permeable resin member (A ′) and non-permeable resin member (B ′) manufactured on the same production line, respectively, according to the detection result. It is preferable to weld the contact surface by irradiating a laser beam having a diameter. As a result, when the same product is repeatedly produced, the same resin member is naturally used. However, since the resin member usually has the same degree of sink and warp at a certain position, as described above. This is because if a gap is detected in the first one scan and then a sequence is set up so that the spot diameter when passing through the part is increased, the detection work need not be repeated.

  Further, as shown in FIG. 7, the gap detection laser and the welding laser as described above can be combined to synchronize the gap detection and the spot diameter adjustment. By this method, since it is not necessary to perform laser scanning a plurality of times, it is possible to perform welding efficiently and reliably.

In the present invention, the laser beam used for the gap detection laser is not particularly limited as long as it can detect the gap without adversely affecting the member, but the same laser beam as the above welding laser should be used. Can do.
When using the above-described gap detection laser light, it is necessary to use laser light that heats the member below the melting temperature of the transmissive resin member and the non-permeable resin member. For example, it can be heated below the melting temperature of the member by reducing the output or increasing the wavelength of the laser light as compared with the welding laser light. Preferably, the wavelength of the gap detection laser light is increased to about 800 to 940 nm. For example, when the wavelength of the gap detection laser beam is 940 nm, the gap can be detected without adversely affecting the member.

[Resin used for resin members]
In the present invention, the resins for forming the permeable resin member (A) and the non-permeable resin member (B) are preferably the same resin, but may be different resins as long as they can be welded. A thermoplastic resin whose volume is more easily expanded by heating and melting than the solid state is preferable.
Specifically, polyethylene, polypropylene, polystyrene, ABS resin, poly (meth) acrylate, polyvinyl chloride, polyamide, polyacetal, polycarbonate, modified polyphenylene ether, polyethylene terephthalate, polybutylene terephthalate, polyphenylene sulfide, polyimide, polyamideimide, polyetherimide , Polyarylate, polysulfone, polyethersulfone, polyetherketone, polyetheretherketone, liquid crystal polymer and the like.

As the resin for forming the permeable resin member (A) (also referred to as “permeable resin”), the above resin is used, and the resin for forming the non-permeable resin member (B) (“non-transmissive”). The resin is also the same resin as the permeable resin member, but may be a resin different from the permeable resin as long as it can be welded. For example, when the non-transparent side polyphenylene sulfide is used as the transmission side polycarbonate, the melting point of the polycarbonate is lower than the melting point of the polyphenylene sulfide. Therefore, when the polyphenylene sulfide melts, the polycarbonate also melts. Moreover, since the transmittance | permeability of a polycarbonate is high, its efficiency is also good.
In addition, as the non-permeable resin, the resin itself can be used, but preferably, an inorganic or organic additive such as carbon black is added to the resin in order to absorb laser light and promote heat generation. Is used. These addition amounts are 0.05-40 weight part with respect to 100 weight part of resin, Preferably it is 0.1-30 weight part. Alternatively, a reinforcing material may be added or the thickness may be increased to absorb laser light.

The permeable resin may further contain various resin additives, fillers, reinforcing materials, resin modifiers, and the like as necessary. Specifically, reinforcing fibers such as glass fibers and carbon fibers, and coloring materials can be added. These addition amounts are 0-70 weight part with respect to 100 weight part of permeable resin, Preferably it is 0-30 weight part.
Similarly, in addition to the above-mentioned predetermined colorants such as carbon black, dyes and pigments, the non-permeable resin further includes various resin additives, fillers, reinforcing materials, flame retardants, if necessary. A resin modifier or the like may be contained. Specifically, those added with reinforcing fibers such as glass fibers and carbon fibers may be used. These addition amounts are 0 to 200 parts by weight with respect to 100 parts by weight of the non-permeable resin.

[Molded body]
The laser welding method of the resin member of the present invention efficiently obtains a high-quality molded product that has stable welding strength and does not protrude from the welded portion, dullness or deformation of the molded product even if there is a gap in part. Because it is a laser welding method of resin members that can be used, for example, even if there is a gap made of sink or warp on the contact surface of both resin members, a resin molded product can be provided efficiently and with a high yield Is possible. Further, even a member that is not highly purified can similarly provide a resin molded product with high efficiency and high yield.
Specifically, according to the present invention, a resin molded product can be efficiently manufactured without impairing the aesthetic appearance even in a complicated shape in automobile parts, headlamps, and the like that are desired to be reduced in weight.
Therefore, the present invention can greatly reduce the production efficiency and the production cost, and its industrial value is great.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto without departing from the gist thereof.
The various physical properties in the examples were measured according to the following procedures.

[Measuring method]
(1) Gap distance measurement method Device name: A gap at the contact portion was measured using a temperature measuring device manufactured by Hamamatsu Photonics.
(2) Appearance of welded portion The presence or absence of foaming and burning of the welded portion was visually confirmed.
(3) Weld strength Tensile tests were performed in the direction perpendicular to the weld line using the actual product, and the fracture strength was measured to obtain the weld strength. The breaking strength is a value when the device name is a tensile device manufactured by Shimadzu Corporation and the tensile speed is 5 mm / min. The breaking strength is at a practical level of 10 MPa or more.

[Examples and Comparative Examples]
Example 1
Non-permeable resin member: using a resin composition comprising 40% by weight of polypropylene resin, 30% by weight of styrene elastomer and 30% by weight of talc, and having a flange with a width of 5 mm at the top, 120 × 100 × 70 × thickness A rectangular parallelepiped container having a top opening of 2 mm was prepared. A laser light absorber (900NP manufactured by Fuji Film) was applied to the flange. Further, this flange was provided with a back rib having a width of 3 mm on a part of the lateral side, and sink marks were visually observed in the rib portion.
FIG. 8A is a schematic view showing the resin member used in this example, and is a view of the resin member to be welded as seen from the laser light irradiation direction. Sink marks were observed in a part of the rib portion of the flange. FIG. 8B is a schematic view showing a cross section of the rib. When the width of the cross section was measured, it was 3 mm.
Translucent resin member: Using polymethylmethacrylate, a rectangular parallelepiped container having an upper opening of length 120 × width 100 × height 70 × thickness 2 mm having a flange 5 mm wide at the top was prepared.
Welding: The permeable resin member and the non-permeable resin member are overlapped so that the flange portions of the non-permeable resin member and the normal portion of the permeable resin member face each other. All four sides were laser welded so that FIG. 9 shows a schematic view of the superimposed members.
As the laser light, a laser device having a wavelength of 940 nm was used using a laser device manufactured by Hamamatsu Photonics.
Welding conditions are: normal part spot diameter 1.8mmφ, output 30W, scan speed 3m / min, gap part corresponding to sink part (gap: 100μm) is defocused by narrowing the distance between laser source and member The spot diameter was 3.6 mmφ. The output was increased to 120 W and the irradiation energy was made substantially the same as that of the normal part. The scan speed was 3 m / min.
Measurement of Weld Strength: FIG. 9 is a schematic diagram illustrating a test piece used for measurement of weld strength in this example. When one side including the sink part, 10 mm in the welding direction × 40 mm in the vertical direction was cut out and a tensile test was performed in a direction perpendicular to the welding line, the breaking strength was 13 MPa.
The evaluation results are shown in Table 1.

(Comparative Example 1)
Welding was performed in the same manner as in Example 1 except that welding was performed at a power of 30 W and a spot diameter of 1.8 mmφ without changing the welding conditions between the normal part and the gap part and without changing the spot diameter. That is, the members manufactured on the same production line as in Example 1 were used, and welding was performed in the same manner as in Example 1 with the welding conditions such as laser light, gap portions, and scanning speed.
Measurement of welding strength: One side including a sink part, 10 mm in the welding direction × 40 mm in the vertical direction, and a tensile test was performed in a direction perpendicular to the welding line, the fracture strength was 3 MPa. Foaming and burning occurred in the gap, and the appearance deteriorated.
The evaluation results are shown in Table 1.

(Example 2)
In Example 1, the normal part of the horizontal side of the impermeable resin member was cut to a depth of 50 μm over a flange width direction of 5 mm × length of 3 mm. The cut portion was regarded as a gap portion.
Welding: Superimposing the permeable resin member and the non-permeable resin member so that the flanges face each other so that the cut portion of the non-permeable resin member and the normal portion of the permeable resin member face each other, so that a gap portion is included. Four sides were laser welded.
As the laser beam, an apparatus having a wavelength of 940 nm was used using a laser apparatus manufactured by Hamamatsu Photonics.
The welding conditions are: normal part spot diameter 1.8 mmφ, output 30 W, scanning speed 3 m / min, gap part (gap: 50 μm) is defocused by narrowing the distance between the laser source and the member, and the spot diameter is 2 It was set to 7 mmφ. The output was increased to 70 W and the irradiation energy was made substantially the same as that of the normal part. The scan speed was 3 m / min.
When one side including the gap portion, 10 mm in the welding direction × 40 mm in the vertical direction was cut out and a tensile test was performed in a direction perpendicular to the welding line, the fracture strength was 15 MPa.
The evaluation results are shown in Table 1.

(Example 3)
In Example 1, evaluation was performed in the same manner as in Example 1 except that the spot diameter of the normal part was 1.98 mmφ, the output was 36 W, the spot diameter of the gap part was 3.96 mmφ, and the output was 145 W. The evaluation results are shown in Table 1.

Example 4
In Example 2, evaluation was performed in the same manner as in Example 2 except that the spot diameter of the normal part was 1.98 mmφ, the output was 36 W, the spot diameter of the gap part was 2.97 mmφ, and the output was 85 W. The evaluation results are shown in Table 1.

(Example 5)
In Example 1, as a welding condition, the spot diameter of the normal part was 1.8 mmφ, the output was 36 W, the spot diameter of the gap part was 3.96 mmφ, and the output was 145 W. Here, the spot diameter of the gap part was a lens having a small refractive index. Evaluation was performed in the same manner as in Example 1 except that defocusing was performed by extending the focal length. The evaluation results are shown in Table 1.

(Example 6)
The gap distance of the first embodiment is measured by measuring the gap distance in advance by temperature measurement using the same material and apparatus as in the first embodiment, changing the spot diameter by defocusing the portion where there is a gap as a sequence, and the output is also matched with the spot diameter. It was made almost equivalent to the irradiation energy of a certain part. That is, the gap distance was detected only for one scan before the start of the welding test, and 150 welding parts were continuously produced under the same welding conditions. The welding strength of the product was maintained at 10 MPa or more, and stable production was possible.

(Comparative Example 2)
In Example 1, evaluation was performed in the same manner as in Example 1 except that the output of the gap portion was set to 30 W. The evaluation results are shown in Table 1.

[Evaluation]
As is apparent from Table 1, the specific matter of the manufacturing method of the present invention is “the size of the gap between the two members generated on the contact surface between the permeable resin member (A) and the non-permeable resin member (B). In accordance with the method that does not satisfy the requirement that “the spot diameter of the laser beam irradiated to the contact surface is changed accordingly”, Comparative Example 1 causes foaming and burning in the appearance of the welded portion, and the welding strength is weak. Comparative Example 2 by a method that does not satisfy the requirement that “the laser beam irradiation energy (J / mm ² ) per unit area on the contact surface is kept substantially the same” is lower than that in which the welding strength is weak, In Examples 1 to 6 according to the production method of the present invention, it has become clear that there is no problem in the appearance of the welded portion and the weld strength is sufficiently strong.
Therefore, the manufacturing method of the present invention can obtain a high-quality molded product with sufficient welding strength, no protrusion of the welded portion, and no dullness or deformation of the molded product, even if there is a gap in part. It is clear that excellent results have been obtained and have great technical significance.

According to the method of the present invention, it is possible to efficiently obtain a high-quality molded product that has stable welding strength and does not protrude from the welded portion or dull or deform the molded product even if there is a gap in some parts. . Therefore, for example, in automobile parts and headlamps that require weight reduction, it is possible to efficiently produce resin molded products without compromising aesthetics even if they have complicated shapes, and greatly reduce production efficiency and production costs. Can do. Therefore, the laser welding method and resin molded product of the resin member of the present invention are very useful in industry.

Claims (12)

In a laser welding method of welding a transparent resin member (A) that transmits laser light by irradiation with laser light and a non-transparent resin member (B) that does not transmit laser light,
According to the size of the gap between the two members generated on the contact surface between the permeable resin member (A) and the non-permeable resin member (B), the spot diameter of the laser light irradiated on the contact surface is changed, and A laser welding method of a resin member, characterized in that the laser beam irradiation energy (J / mm ² ) per unit area on the contact surface is kept substantially the same.   The spot diameter of the laser beam is changed so as to increase as the size (distance) of the gap between the two members formed on the contact surface between the transparent resin member (A) and the non-transmissive resin member (B) increases. The method for laser welding a resin member according to claim 1. The laser beam spot welding method according to claim 1 or 2, wherein the spot diameter of the laser beam satisfies a relationship of the following formula (1).
A _d ≧ 0.012d + A ₀ formula (1)
(In the formula, _Ad is the spot diameter [mm] of the laser beam on the contact surface when the distance between the transparent resin member (A) and the non-permeable resin member (B) is d, and d is the transmitted light. The clearance distance [μm] between the transparent resin member and the non-permeable resin member, A ₀ is the contact surface when the distance between the transparent resin member (A) and the non-permeable resin member (B) is 0 Represents the spot diameter [mm] of the laser beam at.)   The laser beam irradiation energy per unit area on the contact surface is kept substantially the same by changing the laser beam irradiation output (W) and / or the laser beam scanning speed (mm / sec). The laser welding method of the resin member of any one of Claims 1-3.   The laser welding method according to any one of claims 1 to 4, wherein the spot diameter of the laser light is changed by adjusting a distance between a laser light source and a contact surface.   The laser welding method according to any one of claims 1 to 4, wherein the spot diameter of the laser beam is changed by adjusting a focal length of the laser beam.   The laser welding method according to any one of claims 1 to 4, wherein the spot diameter of the laser light is changed by adjusting an irradiation angle between the optical axis of the laser light and the contact surface.   Prior to welding by the laser light irradiation, the size (distance) of the gap between the two members generated on the contact surface between the transparent resin member (A) and the non-permeable resin member (B) is detected in advance. The laser welding method for a resin member according to any one of claims 1 to 7.   The method for laser welding a resin member according to claim 8, wherein the size (distance) of the gap is detected by any one of an optical method, an electrical method, and a thermal method.   Detection of the size (distance) of the gap is performed by irradiating the contact surface with a laser beam that heats the member below the melting temperature of the permeable resin member (A) and the non-permeable resin member (B). 9. The method for laser welding a resin member according to claim 8, wherein the temperature is measured on the contact surface at that time.   Prior to the welding by the laser light irradiation, after detecting the size (distance) of the gap between the two members generated on the contact surface between the transparent resin member (A) and the non-permeable resin member (B) in advance, A laser beam having a spot diameter determined according to the detection result is applied to a contact surface between another transparent resin member (A ′) and non-permeable resin member (B ′) manufactured on the same manufacturing line. And the said contact surface is welded, The laser welding method of the resin member of any one of Claims 1-7 characterized by the above-mentioned. The welding resin molded product obtained by the laser welding method of the resin member of any one of Claims 1-11.

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