JP4857887B2 - Laser welding laser absorbent, laser welding resin composition, molded product and method for producing molded product - Google Patents

Description

  The present invention relates to a laser welding laser absorbent that absorbs laser light, a laser welding composition containing the laser light absorbent, a molded article, and a method for producing the molded article. More particularly, the present invention relates to a laser welding laser absorber that absorbs laser light in a wavelength range of at least 700 to 1200 nm, a laser welding composition containing the laser light absorber, a molded product, and a method for manufacturing the molded product.

The method of joining plastic molded parts is roughly divided into chemical joining technology using an adhesive or the like and physical joining technology such as laser welding, vibration welding, ultrasonic welding, hot plate welding described in Non-Patent Document 1, for example. Is done. Since physical bonding is a bonding technique that does not use a solvent, it is characterized in that sufficient adhesive strength can be obtained even with materials difficult to bond with an adhesive, and the tact time is short. However, in vibration welding, ultrasonic welding and hot plate welding, the shape of the resin suitable for welding is limited, and it is represented by a combination of polyethylene terephthalate (melting temperature 270 ° C.) and polycarbonate (melting temperature 225 ° C.). In recent years, laser welding technology has been used as an alternative technology for these because it cannot be applied to welding between resins with melting points and is limited to joining unexposed parts due to the appearance of the welded part. Particular attention has been paid.

  In laser welding, a molded part (laser-transmitting resin member) that is transparent to laser light as a heating source is brought into contact with a molded part that is absorbent to the laser light (laser-absorbing resin member). The laser beam is irradiated from the laser transmitting resin member side toward the corresponding contact portion. As a result, the laser light transmitted through the laser transmitting resin member reaches the contact end portion of the laser absorbing resin member and is absorbed, and the laser light absorbed in the contact end portion is accumulated as energy. As a result, the laser absorbing resin is heated and melted, and the contact end portion of the laser transmitting resin member is heated and melted by heat transfer from the contact end portion of the laser absorbing resin member. In this state, if the contact end portions of both molded members are pressure-bonded, they can be joined together.

  Laser welding can be performed in a state where the laser and the workpiece are not in contact with each other, so that it is possible to join members that are difficult to directly contact the machining means and the workpiece, 3D welding / precision It can be processed, a free welding shape can be achieved, it has a high welding strength, it has an excellent appearance, there is no generation of dust that becomes a problem with ultrasonic welding, etc., it is easy to automate, etc. Therefore, a wide variety of introductions such as lamps, electrical parts, mounting parts for automobiles such as centers and tanks, medical instruments having joint parts such as syringes and filter cases, plugs and cases related to OA equipment are expected.

  For example, Patent Document 1 describes a method of laser welding while suppressing the occurrence of stress cracks in the body by bringing a PC lens of a vehicle lamp into contact with the body and obliquely irradiating laser light. Yes. However, conventionally used laser absorbers mainly contain carbon black, which is advantageous in terms of price, in a high ratio in order to obtain high laser absorption efficiency. However, in many cases, the use of carbon black causes deterioration of mechanical properties such as toughness, and deterioration of surface quality due to promotion of crystallization. In addition, the color tone of the member is limited from dark to black, making it difficult to color to other colors. This is a particularly big problem in the medical device field where there are many transparent and translucent parts.

As an attempt to reduce the carbon black content, the composition containing the laser-transmissive thermoplastic resin material has a carbon black content of less than 0.1% by weight and contains an IR-absorbing dye such as a naphthalocyanine compound. The thing is proposed (refer patent document 2). However, naphthalocyanine compounds generally have a color tone from blue to green, and there is still a limit to the degree of freedom in coloring. Further improvements are desired in terms of laser sensitivity.
Kunststoffe 87, (1997), 11,1632-1640 JP 2002-292741 JP 2003-183524 A

  The present invention has been made in view of the above circumstances, and its object is to have excellent solubility in resins, particularly thermoplastic resin materials, and high absorption sensitivity in the wavelength range of 700 to 1200 nm, particularly 700 to 900 nm. Another object of the present invention is to provide a laser welding laser absorbent having low absorption sensitivity in the visible region and excellent in light resistance and heat resistance. Also provided are a resin composition for laser welding having a high absorption sensitivity in a wavelength range of 700 to 1200 nm, particularly 800 to 1000 nm, a molded article obtained using the composition, and a method for producing a molded article by laser welding. It is.

As a result of intensive studies to solve the above problems, the present inventors have found that a dioxadinaphthopentacene compound having a specific structure is excellent in solubility in a thermoplastic resin material, and at least a part of the wavelength region of 700 to 1200 nm. The present invention was completed by finding that the range showed very strong absorption and that there was little absorption that was visible in the visible region and that it was close to an achromatic color by visual observation.
That is, the gist of the present invention resides in a laser welding laser absorbent comprising a dioxadinaphthopentacene compound represented by the following general formula (1).

(In the formula, rings A, B, C, D and E each independently represent a benzene ring optionally having any substituent, but a plurality of substituents on the same ring are linked to form a ring. A, B, C, D and E may each independently form a condensed ring, and X and Y each independently represent an oxygen atom, a sulfur atom, = C (CN) ₂ , = C (CN) COOR , = C (CN) CONRR 'or = N-C≡
N (wherein R and R ′ each independently represents a hydrogen atom or an arbitrary substituent), but at least one of X and Y represents a group other than an oxygen atom. Z and Z ′ each independently represent an oxygen atom, a sulfur atom or —NR ″ — (where R ″ represents a hydrogen atom or an arbitrary substituent). )
Another gist lies in a resin composition for laser welding characterized by containing a thermoplastic resin and the above laser absorber.

Still another gist is a molded article joined by laser welding, wherein at least one molded part constituting the molded article is composed of the above-mentioned resin composition for laser welding. , Exist.
Still another subject matter is: (1) a step of contacting a molded part that is transparent to laser light as a heating source and a molded part that is absorbent to the laser light; and (2) In the method of manufacturing a molded product, the method includes the step of irradiating the laser beam from the side of the molded component having transparency to the laser beam, and heating and melting the contact surfaces of both molded components together. The molded part manufacturing method is characterized in that a molded part having absorptivity to the above is a molded part made of the above laser welding resin composition.

  The laser-absorbing laser absorbent of the present invention is excellent in solubility in thermoplastic resins and absorption sensitivity to near-infrared light, but has low absorption sensitivity in the visible region. Therefore, the laser welding resin composition containing the laser absorbent and the transparent thermoplastic resin is excellent in laser absorption sensitivity, and can be made almost transparent to the naked eye. A freely colored resin composition can be obtained. In addition, when the color tones of the resins used for the laser-absorbing resin member and the laser-transmitting resin member are the same or close to each other, the dyes added for the purpose of coloring can have almost the same composition. Further, by using this resin composition as a laser-absorbing resin member, resin welding can be performed with low laser power.

Embodiments of the present invention will be specifically described below, but the present invention is not limited to the following embodiments, and various modifications can be made within the scope of the gist of the present invention.
The present invention relates to a laser welding laser absorbent, a laser welding resin composition, a molded article, and a method for producing the molded article. Hereinafter, a laser welding laser absorbent is a composition containing the absorbent by laser irradiation. Meaning a laser absorber used for the purpose of bonding by utilizing the phenomenon that an object melts and adheres to a substance other than the composition, typically a composition comprising a thermoplastic resin and the laser absorber Used for laser welding. Moreover, the resin composition for laser welding means a resin composition used for the purpose of bonding by utilizing a phenomenon that the composition melts by laser irradiation and adheres to a substance other than the composition.
1. Laser absorber The laser absorber for laser welding according to the present invention comprises a dioxadinaphthopentacene compound represented by the following general formula (1).

(In the formula, rings A, B, C, D and E each independently represent an optionally substituted benzene ring, but a plurality of substituents on the same ring are linked to form ring A. , B, C, D and E may each independently form a condensed ring, X and Y are each independently an oxygen atom, a sulfur atom, = C (CN) ₂ , = C (CN) COOR, = C (CN) CONRR ′ or ═N—C≡N (where
R and R ′ each independently represents a hydrogen atom or an arbitrary substituent, and at least one of X and Y represents a group other than an oxygen atom. Z and Z ′ each independently represent an oxygen atom, a sulfur atom or —NR ″ — (where R ″ represents a hydrogen atom or an arbitrary substituent). )
Hereinafter, in the present specification, “may have a substituent” means that it may have one or more substituents.

1-1) Rings A, B, C, D and E Rings A, B, C, D and E in formula (1) each independently represent a benzene ring optionally having an arbitrary substituent. As shown, a plurality of substituents on the same ring may be connected to form rings A, B, C, D and E independently of each other to form a condensed ring. As the ring A, B, C, D and E are substituent which may have, A alkyl group, a haloalkyl group, an alkoxy group, alkoxyalkoxy group, a halogen atom, a hydroxyl group, a carboxyl group, an alkylcarbonyl group or an alkoxycarbonyl A group , preferably an alkyl group, a haloalkyl group, an alkoxyalkoxy group, a carboxyl group or an alkoxycarbonyl group.

As the alkyl group, an alkyl group having 1 to 8 carbon atoms such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a heptyl group, a hexyl group, and an octyl group, preferably an alkyl group having 1 to 6 carbon atoms. Is mentioned.
As a haloalkyl group, a C1-C8 haloalkyl group substituted by a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, Preferably a C1-C6 haloalkyl group is mentioned.

Moreover, as an alkoxy group, C1-C8 alkoxy groups, such as a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentyloxy group, a heptyloxy group, a hexyloxy group, an octyloxy group, Preferably it is carbon number 1 ˜6 alkoxy groups.
The alkoxyalkoxy group is an alkoxyalkoxy group having 2 to 8 carbon atoms, preferably an alkoxyalkoxy group having 2 to 6 carbon atoms, such as a methoxyethoxy group, an ethoxyethoxy group, a methoxypropoxy group, or a butoxyethoxy group. It is done.

  Examples of the halogen atom include a fluorine atom, a bromine atom, a chlorine atom, and an iodine atom. As the alkylcarbonyl group, an alkylcarbonyl group having 1 to 8 carbon atoms such as an acetyl group, an ethylcarbonyl group, a propylcarbonyl group, a butylcarbonyl group, a pentylcarbonyl group, a heptylcarbonyl group, a hexylcarbonyl group, and an octylcarbonyl group is preferable. Is an alkylcarbonyl group having 1 to 6 carbon atoms.

  The alkoxycarbonyl group has 1 carbon atom such as acetyloxycarbonyl group, ethyloxycarbonyl group, propyloxycarbonyl group, butyloxycarbonyl group, pentyloxycarbonyl group, heptyloxycarbonyl group, hexyloxycarbonyl group, octyloxycarbonyl group, etc. -8 alkoxycarbonyl groups, preferably an alkoxycarbonyl group having 1 to 6 carbon atoms.

The alkyl group portion in the alkyl group, haloalkyl group, alkoxy group, alkoxyalkoxy group, carboxyl group, alkylcarbonyl group and alkoxycarbonyl group may be linear or cyclic, and may be linear or branched. .
When a plurality of substituents on the same ring in rings A, B, C, D, and E are linked to form rings A, B, C, D, and E each independently form a condensed ring, the substituents are linked. Examples of the ring formed include aromatic hydrocarbon rings such as benzene rings, aromatic heterocyclic rings such as pyridine rings and thiophene rings, and alicyclic hydrocarbon rings such as cyclohexyl rings. Aromatic hydrocarbon rings are desirable, and the condensed aromatic hydrocarbon rings A, B, C, D and E are preferably condensed aromatic hydrocarbon rings having 10 to 12 carbon atoms such as naphthalene ring and anthracene ring. .

1-2) X and Y In the formula (1), X and Y are each independently an oxygen atom, a sulfur atom, ═C (CN) ₂ , ═C (CN) COOR, ═C (CN) CONRR ′ or ═N—C≡N (wherein R and R ′ each independently represents a hydrogen atom or an arbitrary substituent), but at least one of X and Y represents a group other than an oxygen atom. When both X and Y are oxygen atoms, there is a problem that the maximum absorption wavelength is shortened and it is not suitable for laser welding or is colored.

R and R ′ preferably represent an alkyl group or an aryl group which may have a substituent, and particularly preferably a linear or branched chain having 1 to 8 carbon atoms or 1 to 4 carbon atoms. It is an alkyl group. Specific examples of the linear or branched alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, and a butyl group.
At least one of X and Y is preferably ═C (CN) ₂ from the viewpoint of the absorption wavelength, and particularly preferably both X and Y are C— (CN) ₂ .

1-3) Z and Z ′ In the above formula (1), Z and Z ′ each independently represent an oxygen atom, a sulfur atom or —NR ″ — (where R ″ represents a hydrogen atom or an arbitrary substituent) .) R ″ preferably represents an alkyl group or an aryl group which may have a substituent, and particularly preferably a linear or branched alkyl group having 1 to 8 carbon atoms and 1 to 4 carbon atoms. It is. Specific examples of the linear or branched alkyl group having 1 to 4 carbon atoms include the same groups as described above.
Z and Z ′ are preferably an oxygen atom or a sulfur atom, and particularly preferably an oxygen atom.

1-4) Particularly Preferred Compounds Among the dioxadinaphthopentacene-based compounds represented by the above general formula (1), the following general formula (X) wherein X and Y in the general formula (1) are = C (CN) ₂ The compound represented by 2) is particularly preferred in terms of absorption wavelength and molecular extinction coefficient.

(Wherein R ^{1 to} R ⁸ each independently represents a hydrogen atom, an alkyl group, a haloalkyl group, an alkoxy group, an alkoxyalkoxy group, a halogen atom, a hydroxyl group, a carboxyl group, an alkylcarbonyl group or an alkoxycarbonyl group, or R ¹ and R ² , R ³ and R ⁴ , R ⁵ and R ⁶ and R ⁷ and R ⁸ are bonded to each other to form a ring, and R ⁹ and R ¹⁰ are each independently a hydrogen atom or a halogen atom. Or an alkyl group, and Z and Z ′ each independently represents an oxygen atom or a sulfur atom.)
As the alkyl group, haloalkyl group, alkoxy group, alkoxyalkoxy group, halogen atom, alkylcarbonyl and alkoxycarbonyl group represented by R ^{1 to} R ⁸ in the general formula (2), ring A in the general formula (1), Examples of the substituents for B, C, D and E include the same groups as the alkyl groups, haloalkyl groups, alkoxy groups, alkoxyalkoxy groups, halogen atoms, carboxyl groups, alkylcarbonyl groups and alkoxycarbonyl groups. Preferred substituents The specific substituents are also the same as described above.

R1 to R8 may be the same or different from each other, but are preferably the same in terms of synthesis.
In addition, when at least part of R ¹ and R ² , R ³ and R ⁴ , R ⁵ and R ⁶ and R ⁷ and R ⁸ are bonded to form a ring, the ring formed is the same as described above An aromatic hydrocarbon ring, an aromatic heterocyclic ring, or an alicyclic hydrocarbon ring is exemplified, and among them, an aromatic hydrocarbon ring such as a benzene ring is preferable.

In addition, as the halogen atom and alkyl group represented by R ⁹ and R ¹⁰ in the general formula (2), the halogen atom described as a substituent of the rings A, B, C, D and E in the general formula (1) And alkyl groups, and preferred substituents and specific substituents are the same as described above.
1-5) Physical properties of the compound represented by the general formula (1) The compound represented by the general formula (1) preferably has high absorptivity with respect to the laser used in laser welding. From this point, it is preferable that the absorption maximum of a solution obtained by dissolving the above compound in a chloroform solvent at a concentration of 0.01 g / mol exists in the wavelength range of 700 to 1200 nm, and particularly preferably in the wavelength range of 800 to 1000 nm. The extinction coefficient (ε) is preferably 10,000 or more. Moreover, since it is preferable that it is almost achromatic color visually, it is preferable that the light absorbency in the range of 400-650 nm in the chloroform solution of 0.01 g / mol concentration is 0.2 or less.

The compound represented by the general formula (1) usually has a molecular weight of 2000 or less, particularly 1500 or less, particularly preferably 1000 or less, in terms of absorbance per weight.

In addition, the compound represented by the general formula (1) which is laser welding is usually mixed with a resin such as a thermoplastic resin and used as a laser welding resin composition, and is therefore soluble in the resin. Is preferably high. Conversely, it is usually water-insoluble. Here, “water-insoluble” means that the solubility in water at 25 ° C. and 1 atmosphere is usually 0.01% by weight or less, preferably 0.001% by weight or less.

1-6) Specific examples of compound represented by general formula (1) Preferred specific examples of the dioxadinaphthopentacene compound of the present invention represented by general formula (1) include those exemplified below. Is mentioned. However, it is not limited to the following compounds.

1-7) Synthesis Method The dioxadinaphthopentacene compound represented by the general formula (1) can be easily synthesized according to a known method described in JP-A-63-297385. For example, the dioxadinaphthopentacene compound represented by the general formula (2) is represented by the following general formula (3)

(In the formula, R ^{1 to} R ¹⁰ , Z and Z ′ are the same as defined in the general formula (2).)
Can be produced by reacting malononitrile (CH ₂ (CN) ₂ ) with chloroform in the presence of pyridine and titanium tetrachloride.
The laser welding laser absorbent of the present invention described above absorbs light in a wavelength band of 700 to 1200 nm, particularly 800 to 1000 nm, and exhibits a large molecular extinction coefficient, while in the visible light wavelength region of 400 to 650 nm. There is little conspicuous light absorption. It is excellent in light resistance, heat resistance, compatibility with resin, and easy to manufacture. The resin composition for laser welding containing such a laser absorbent can be welded with a low laser power even if the amount of the laser absorbent used is relatively small. The laser welding resin composition containing this laser absorbent and a transparent thermoplastic resin is excellent in laser absorption sensitivity, but can be made almost transparent to the naked eye, and can be freely combined with other dyes. It is possible to make a colored resin composition.

2. Laser welding resin composition The laser welding resin composition of the present invention contains a thermoplastic resin and the laser absorbent of the present invention represented by the general formula (1).

  The thermoplastic resin is not particularly limited as long as it is a thermoplastic resin having laser transparency. Here, having laser transparency means that at any layer thickness of 0.4 to 6 mm, the laser transmittance of at least part of the wavelength range of 700 to 1200 nm or this spectral range is 5% or more. means. The laser transmittance is preferably 0.5 to 5 mm, particularly preferably 0.6 to 3.5 mm, and the transmittance is preferably 5% or more. The laser transmittance is preferably 10% or more, more preferably 15% or more.

In the molded product and the method for producing the molded product described later, 50% or more of the irradiated laser is transmitted as the thermoplastic resin constituting the thermoplastic resin composition, depending on the thickness of the molded product. A thermoplastic resin having a laser transmittance is selected.
Examples of the thermoplastic resin of the present invention include polyolefin resins such as polyethylene, polypropylene, and propylene-ethylene copolymers, styrene resins such as acrylonitrile / butadiene / styrene, acrylonitrile / styrene, polystyrene, acrylonitrile / ethylene propylene rubber / styrene, Polyvinyl alcohol, saponified ethylene / vinyl acetate copolymer, vinyl chloride, polyamide (PA6 PA66, etc.), polyester (polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc.), polycarbonate, polyoxymethylene, polyphenylene sulfide, polyphenylene ether, Examples thereof include polyether ether ketone, and these may be used as a mixture. In addition, olefin-based thermoplastic elastomers and styrene-based thermoplastic elastomers can also be used.

  The content of each component in the resin composition for laser welding of the present invention is usually 97% by weight or more, preferably 99.7% by weight or more, and usually 99.999% by weight or less for the thermoplastic resin. Moreover, the content rate of a laser absorber is 0.001 to 3 weight% normally. In addition, the laser absorber of this invention represented by General formula (1) is independent, or may use 2 or more types together, and when 2 or more types of laser absorbers are contained, the ratio is arbitrary. Yes, usually the sum is within the above range. If the content of the laser absorber of the present invention is too low, the necessary laser absorption amount may not be ensured, and sufficient laser weldability may not be obtained. There will be no.

  The resin composition for laser welding according to the present invention can contain various additives in addition to the thermoplastic resin and the laser absorbent according to the present invention represented by the general formula (1) depending on the application. Such additives include auxiliary colorants, dispersants, fillers, stabilizers, plasticizers, modifiers, UV absorbers or light stabilizers, antioxidants (phenolic, phosphorus, sulfur, etc.), charging Inhibitors, lubricants, release agents, crystallization accelerators, nucleating agents, flame retardants (halogen-based, phosphorus-based), inorganic fillers (talc, calcium carbonate, glass fibers, carbon fibers, whiskers, silica, barium sulfate, zeolite, Clay, magnesium hydroxide, aluminum hydroxide, magnesium carbonate, carbon nanofiber), elastomer for improving impact resistance, singlet oxygen quencher, etc., the content of which depends on the use of the resin composition Thus, it is appropriately selected from a known range.

  The laser welding resin composition of the present invention can be obtained by mixing individual components according to a known method. For mixing with the resin, a known method such as mixing with a blender or mixer, solid kneading after hand blending, melt kneading, adding to the resin after melting, or adding at the time of molding with a masterbatch is used. It is possible. A conventionally known apparatus can be used for the melt-kneading, and examples thereof include an internal kneader, a single-screw extruder, a multi-screw extruder, a roll, and a Banbury mixer. The mixing is performed in a temperature range where the resin does not thermally decompose and a predetermined viscosity is obtained. In addition, the additive mentioned above can also be added in the middle of melt compounding or melt extrusion processing.

3. Manufacturing method of molded product The manufacturing method of the molded product of the present invention includes (1) a molded part that is transparent to laser light as a heating source (hereinafter, may be abbreviated as a laser light transmitting molded part). A step of abutting a molded part having absorptivity with respect to the laser light (hereinafter sometimes abbreviated as a laser light absorptive molded part), and (2) transparency to the laser light. In the manufacturing method of a molded product, the molded component having the step of irradiating the laser beam from the molded component side and heating and melting the contact surfaces of both molded components together Consists of the resin composition for laser welding of the present invention.
The laser light-transmitting molded part is not particularly limited as long as it is a molded part that substantially transmits the laser light described later used for laser welding. For example, the above-described thermoplastic resin, or molding obtained thereby Examples thereof include molded parts obtained by molding a thermoplastic resin composition containing an arbitrary additive within a range in which the part substantially transmits laser light according to a known molding method such as injection molding or extrusion molding. Here, substantially transmitting the laser beam means that 50% or more of the laser beam is transmitted when the molded part is irradiated with the laser (that is, in the thickness direction of the laser beam irradiation). The permeability of the laser light transmissive molded part is preferably 60% or more.

  In the present invention, the laser-light-absorbing molded part is composed of the above-mentioned laser welding resin composition of the present invention, and the known laser welding resin composition of the present invention is usually formed by known molding such as injection molding or extrusion molding. It is obtained by molding according to the method. Note that it is preferable that the thermoplastic resin constituting the laser light transmitting molded part and the laser light absorptive molded part are the same because the fusing property is good.

  In the method for producing a molded product according to the present invention, after the laser light absorbing molded component and the laser light transmissive molded component are brought into contact with each other, the laser light is irradiated from the laser light transmissive molded component side, These abutting surfaces are heated and melted to form a molded product. Note that the contact is in a state where the welded portion is in direct contact by a method such as lamination or fitting, but a fixing jig or the like may be used as necessary as long as transmission and absorption of laser light are not hindered. .

The type of laser used as the heating source is, for example, YAG: Nd 3 + laser (laser beam wavelength 1060 nm), semiconductor laser (laser beam wavelength 500 to 1000 nm), etc., with a wavelength of 700 to 1200 nm because of the absorption wavelength of the laser absorber. A laser in the range of can be used.
In addition, irradiation conditions such as laser output, irradiation density, and processing speed (moving speed) can be appropriately set according to the type of resin. The irradiation angle of the laser beam with respect to the contact surface may be either vertical or oblique.

Embodiments of the present invention will be described below by way of examples. However, the present invention is not limited to these examples as long as the gist thereof is not exceeded.
Example 1
<Preparation of resin composition>
No. 1 in Table 1 above was synthesized in polypropylene resin pellets (Novatech (registered trademark) PP BC03G manufactured by Nippon Polypro Co., Ltd.) according to the method described in JP-A-63-297385. After adding 1% of the dye represented by No. 27 (λ _max in a 0.01 g / mol chloroform solution: 770 nm) and hand blending, the mixture was charged into a small twin screw extruder KZW-15 (manufactured by Technobel) and cylinder The temperature was set to 150 to 190 ° C., 400 rpm, and the discharge was 1.5 kg / hr, melt kneading and extrusion were performed, and the strand was cut after cooling the water bath to obtain pellets.

<Production of molded body>
[Laser absorption specimen creation]
The obtained pellets were formed into a 2 mm thick flat plate with an injection molding machine IS-55 (Toshiba Machine) under the setting conditions of cylinder temperature setting 150-200 ° C., mold temperature 40 ° C., injection time 15 seconds, cooling time 15 seconds. The test piece was molded and cut into a size of 120 mm × 80 mm.
[Laser transmission specimen]
Polypropylene resin pellets (Novatech (registered trademark) PP BC03G manufactured by Nippon Polypro Co., Ltd.) were injection molded and cut out under the same conditions as the laser absorption test pieces to obtain test pieces.
<Laser welding experiment>
The test piece for laser transmission is placed on the test piece for laser absorption, and a PARK LASER SYSTEM (wavelength: 940 nm) manufactured by Parker Corporation is used. The laser output is 30 W, the laser current is 23 A, and the laser scanning speed is 10 mm / s. As a result of laser irradiation and laser welding experiments, good welding was confirmed. In addition, the irradiation angle of the laser beam with respect to the contact surface was performed perpendicularly.

Claims (5)

A laser welding laser absorber comprising a dioxadinaphthopentacene compound represented by the following general formula (1).

(In the formula, rings A, B, C, D and E each independently represent a benzene ring optionally having any substituent, but a plurality of substituents on the same ring are linked to form a ring. A, B, C, D and E may each independently form a condensed ring, and X and Y each independently represent an oxygen atom, a sulfur atom, = C (CN) ₂ , = C (CN) COOR , = C (CN) CONRR 'or = N-C≡
N (wherein R and R ′ each independently represents a hydrogen atom or an arbitrary substituent), but at least one of X and Y represents a group other than an oxygen atom. Z and Z ′ each independently represent an oxygen atom, a sulfur atom or —NR ″ — (where R ″ represents a hydrogen atom or an arbitrary substituent). ) The laser absorbent for laser welding according to claim 1, wherein at least one of X and Y is = C (CN) ₂ . A laser welding resin composition comprising a thermoplastic resin and the laser absorbent according to claim 1. A molded product joined by laser welding, wherein at least one molded part constituting the molded product is formed of the resin composition for laser welding according to claim 3. (1) a step of contacting a molded part having transparency to laser light as a heating source and a molded part having absorbency with respect to the laser light; and (2) against the laser light. In a method for manufacturing a molded product, the method includes a step of irradiating the laser beam from the side of the molded component having transparency, and joining the contact surfaces of both molded components by heating and melting each other. A method for producing a molded article, wherein the molded part has a molded part made of the laser welding resin composition according to claim 4.