JP2006077160A - Polyoxymethylene resin composition for laser welding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyoxymethylene resin composition having excellent laser welding characteristics without reducing laser beam transmittance when a polyoxymethylene resin is compounded with a colorant. <P>SOLUTION: The polyoxymethylene resin composition for laser welding is composed of a resin composition prepared by compounding 100 pts.wt. of the polyoxymethylene resin with (A) 0.001-5 pts.wt. of the colorant. The laser beam transmittance measured in a molded product prepared from the composition and having 3 mm thickness is ≥15% at 700-1,200 nm wavelength of the laser beams used for the laser welding. For further detail, the polyoxymethylene resin composition for laser welding is characterized in that (A) the colorant contains at least one pigment selected from monoazoic, disazoic, heterocyclic, phthalocyaninic, quinacridonic, perylenic pigments, diketopyrrolopyrrole, isoindolinone, titanium yellow and ultramarine pigments. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a polyoxymethylene resin composition for laser welding.

  Since polyoxymethylene resin has excellent strength characteristics, fatigue characteristics, and electrical characteristics, it is widely used in many fields such as electric parts, office equipment parts, and building materials, and the demand is increasing. In assembling these parts, techniques such as adhesives, screwing, and heat welding have been used. Here, in many cases, the adhesive requires a time loss until it is cured and a fixing jig is required, and the use of a solvent is problematic from the viewpoint of cost increase and environmental protection. In addition, when screwing is performed, there are problems such as costs for insert nuts, screws, washers and the like, labor and time for fastening, and weight.

  On the other hand, welding represented by laser welding, vibration welding, ultrasonic welding, hot plate welding, etc. can be joined in a short time, and metal parts such as adhesives and screws are not used. As a result, problems such as increase in weight and environmental pollution do not occur, and assembly by this method is increasing.

  Patent Documents 1 and 2 disclose a method for producing a molded body by laser welding using a thermoplastic polyester resin.

  As for the adhesion of polyoxymethylene resin, Patent Document 3 discloses a method using a modified olefin copolymer as an adhesive between resins. However, this method has problems such as an increase in the weight of the molded product and insufficient adhesive strength.

  Therefore, for adhesion of a polyoxymethylene resin composition containing an olefin to a polyoxymethylene resin, a molded product can be obtained by using techniques such as hot plate welding, laser welding, and vibration welding in Patent Document 4. Is disclosed. When laser welding is performed, the transparency of the material used to the laser beam is a very important parameter, and in order to perform laser welding, two types of materials that transmit the laser beam and materials that absorb the laser beam are combined. There is a need. Here, Patent Document 4 discloses the use of carbon black as a material as a means for absorbing a laser beam. Carbon black drastically reduces the laser beam transparency of the material and allows the material to absorb the laser beam. The laser beam transmittance is expected to be drastically reduced by adding a coloring pigment other than carbon black to the non-reinforced and non-colored polyoxymethylene resin. Therefore, laser welding is performed. In this case, the possibility of using it as a laser beam absorption side material is considered, but it is very difficult to use it as a laser beam transmission side material. In order to use these materials as the laser beam transmission side material, the thickness of the molded product can be reduced as a means for improving the transparency, but it is considered that the degree of freedom in designing the material is reduced.

Here, even when a coloring pigment is added, the laser beam transmittance of the obtained polyoxymethylene resin composition does not decrease, and it is excellent as a laser beam transmitting side material in performing laser welding, and also has heat resistance and weather resistance. As a result of intensive studies on a polyoxymethylene resin composition having excellent material properties such as properties, the present invention has been achieved.
JP 2001-26656 A (second page) JP 2003-136601 A (second page) JP-A-9-248851 (2nd page) JP 2002-138185 A (page 14)

  An object of the present invention is to obtain a polyoxymethylene resin composition having excellent laser welding characteristics as a laser beam transmission side material without significantly reducing the laser beam transmittance when a color pigment is blended with a polyoxymethylene resin.

  As a result of diligently studying the polyoxymethylene resin composition having excellent laser welding characteristics, the present inventors have solved the above-mentioned problems of the prior art and do not reduce the laser beam transmittance when blended with a color pigment. The present invention has been achieved.

That is, the present invention
-It is a polyoxymethylene resin composition for laser welding formed by blending 0.001 to 5 parts by weight of the colorant (A) with respect to 100 parts by weight of the polyoxymethylene resin, and the wavelength of the laser beam is 700 to 1200 nm. A laser-welded polyoxymethylene resin composition having a laser beam transmittance of 15% or more measured with a molded product having a thickness of 3 mm prepared from the composition,
-Preferably, (A) at least one pigment in which the colorant is selected from monoazo, disazo, heterocyclic, phthalocyanine, quinacridone, perylene, diketopyrrolopyrrole, isoindolinone, titanium yellow, and ultramarine blue Is a polyoxymethylene resin composition for laser welding.

  According to the present invention, when the (A) colorant is blended with the polyoxymethylene resin, it becomes possible to obtain a polyoxymethylene resin composition having excellent laser welding characteristics without drastically reducing the laser beam transmittance.

  Hereinafter, the present invention will be described in detail.

(1) Polyoxymethylene resin The polyoxymethylene resin in the present invention is a homopolymer or a copolymer having an oxymethylene unit. In the present invention, the polyoxymethylene resin is mainly composed of oxymethylene units and has 2 to 8 polymethylene units in the main chain. It is preferable to use an oxymethylene copolymer containing not more than 15% by weight of oxyalkylene units having adjacent carbon atoms.

  As an example of a typical method for producing an oxymethylene copolymer, a high purity trioxane and a copolymer component such as ethylene oxide and 1,3-dioxolane are introduced into an organic solvent such as cyclohexane, and boron trifluoride diethyl ether complex is prepared. A method of producing by cationic polymerization using a Lewis acid catalyst such as deactivation of the catalyst and stabilizing the end groups, or trioxane into a self-cleaning stirrer without using any solvent. Examples thereof include a method in which a copolymer component and a catalyst are introduced and bulk polymerization is performed, and then an unstable terminal is further decomposed and removed.

  The viscosity of these polymers is not particularly limited as long as it can be used as a molding material, but the melt flow rate (MFR) can be measured by the ASTM D1238 method, and the temperature is 190 ° C. and the measurement load is 2,160 g. Below, it is preferable that it is a thing of the range of MFR 0.1-100g / 10min, and it is especially preferable that it is a thing of 1.0-50g / 10min.

  Examples of the solvent for the polymerization catalyst used in the present invention include aromatic hydrocarbons such as benzene and toluene, aliphatic hydrocarbons such as n-hexane, n-heptane and cyclohexane, alcohols such as methanol and ethanol, chloroform, Halogenated hydrocarbons such as dichloromethane, 1,2-dichloroethane, and ketones such as acetone and methyl ethyl ketone are used.

The addition amount of the polymerization catalyst is in the range of 5 × 10 ⁻⁶ to 1 × 10 ⁻¹ mol, particularly preferably in the range of 1 × 10 ⁻⁶ to 1 × 10 ⁻² mol, with respect to 1 mol of trioxane. .

  Various apparatuses for polymerizing trioxane and cyclic ether in bulk are known, but the bulk polymerization used in the present invention is not particularly limited by the apparatus, and if it is 10% by weight or less based on trioxane, The present invention can also be applied to a polymerization reaction performed in the presence of an organic solvent such as cyclohexane. In bulk polymerization, since rapid solidification and heat generation during polymerization occur, an apparatus having a strong stirring ability and capable of controlling the reaction temperature is particularly preferably used. The bulk polymerization apparatus of the present invention having such a performance includes a normal screw extruder having a pair of parallel screws meshing with a long case having a heating or cooling jacket, and two horizontal stirring shafts. And a self-cleaning type mixer that rotates with a slight clearance between the mating paddle surface and the case inner surface when the shaft is simultaneously rotated in the same direction. In bulk polymerization, strong agitation ability is required because it solidifies rapidly in the initial stage of the polymerization reaction, but once solidification, no large agitation ability is required, so a bulk polymerization machine can be used. You may connect and use more than one unit. Furthermore, the bulk polymerization temperature is preferably in the temperature range from the vicinity of the melting point to the boiling point of trioxane, that is, in the range of 60 to 115 ° C.

  Examples of the polymerization terminator used in the present invention include bis (1-octyloxy-2,2,6,6 tetramethyl-4-piperidyl) sebacate and bis (1-octyloxy-2,2,6,6 tetraethyl-4- And amine compounds such as piperidyl) sebacate.

  The added amount of the amine compound of the present invention is preferably such that the number of nitrogen atoms of the amine compound is equal to or more than the number of boron atoms of the boron trifluoride catalyst of the polymerization catalyst used. Even if the number of nitrogen atoms is less than the number of boron atoms, the catalyst deactivation effect can be seen, but since the heat resistance stability of the obtained polymer is slightly reduced, the addition amount is adjusted according to the desired degree of heat stability. There is a need.

  The amine compound for terminating polymerization used in the present invention may be added as it is, but may be added as a solution in an organic solvent in order to enhance the effect of terminating the polymerization reaction. Examples of the organic solvent include aromatic hydrocarbons such as benzene, toluene and xylene, aliphatic hydrocarbons such as n-hexane, n-heptane and cyclohexane, alcohols such as methanol and ethanol, chloroform, dichloromethane, Halogenated hydrocarbons such as 1,2-dichloroethane, and ketones such as acetone and methyl ethyl ketone are used.

  In the present invention, after bulk polymerization using a boron trifluoride-based catalyst to a mixture of trioxane and cyclic ether, a specific nitrogen compound is added as a deactivator to the obtained polymer to deactivate the catalyst, An oxymethylene copolymer is produced by heating to a temperature range of 100 to 270 ° C., preferably a temperature equal to or higher than the melting point of the copolymer. At any stage of this production process, a generally known antioxidant, formaldehyde scavenger, terminal decomposition It is possible to add accelerators. For example, after adding an antioxidant to trioxane, a cyclic ether or a mixture thereof and polymerizing to deactivate the catalyst, the temperature range of 100 to 270 ° C., after polymerizing the trioxane and cyclic ether to deactivate the catalyst , Antioxidant, formaldehyde scavenger, method of adding terminal decomposition accelerator, trioxane, cyclic ether is polymerized to deactivate the catalyst, then antioxidant, terminal decomposition accelerator is added, and 100 to 270 ° C For example, a method of adding a formaldehyde scavenger after heat stabilization in the temperature range is adopted. In the present invention, in the case where a quencher, an antioxidant, a formaldehyde scavenger, and a terminal decomposition accelerator are added in the production process as described above, the mixture is referred to as a polyoxymethylene resin.

(2) (A) Colorant In this case, the colorant may be any colorant as long as the laser beam transmittance of the present invention is 15% or more.

  Specific examples of the colorant (A) used in the present invention include monoazo, disazo, heterocyclic, phthalocyanine, quinacridone, perylene, diketopyrrolopyrrole, isoindolinone organic pigments, titanium Preferred examples include yellow and ultramarine inorganic pigments. Furthermore, as monoazo series, naphthol AS red, metal salt azo yellow, developer hansa yellow, benzimidazolone yellow, benzimidazolone orange, benzimidazolone brown, etc. are available. As the phthalocyanine series, phthalocyanine blue, heliogen blue, cyanine blue, etc. Perylene scarlet etc. are mentioned as a representative example.

  These colorants can be added in an amount of 0.001 to 5 parts by weight. Preferably it is 0.1-3 weight part, More preferably, it is 0.2-2 weight part. If it is less than 0.001 part by weight, the polyoxymethylene resin is not sufficiently colored, and color unevenness occurs, which is not preferable. Further, when the amount exceeds 5 parts by weight, the laser beam transmittance of the polyoxymethylene resin composition is drastically reduced, and when performing laser welding, it is impossible to weld at the time of laser welding with the laser beam absorption side material as the laser beam transmission side material. Therefore, it is not preferable. These colorants can be used in at least one kind.

  Furthermore, when adding an amount that exhibits a sufficient coloring effect alone, inorganic colorants such as cadmium sulfate, cadmium selenide, titanium dioxide, iron oxide, chromate oxide, and carbon black are used as colorants that significantly reduce laser beam transmission. Examples include pigments, organic pigments such as anthraquinone, dioxane, quinophthalone, and berylone, and extender pigments such as calcium carbonate, barium sulfate, talc, clay, and silica. These pigments define the permeability in the present invention. In a range satisfying the laser beam transmittance, it can be added in combination with the colorant having excellent laser beam transmittance of the present invention.

In the present invention, (A) the colorant is at least one selected from monoazo, disazo, heterocyclic, phthalocyanine, quinacridone, perylene, diketopyrrolopyrrole, isoindolinone, titanium yellow, and ultramarine blue. Preferably it contains two pigments.
(3) Other Additives Further, in the present invention, other inorganic fillers, conductive carbon black, metal powder, polyolefin resin, acrylic resin are added to the polyoxymethylene resin composition of the present invention within a range not impairing the effects of the present invention. , A styrene resin, a polycarbonate resin, an uncured epoxy resin, a thermoplastic resin represented by a modified product thereof, a release agent, or the like can be blended. Examples of the release agent include alcohols, fatty acids and esters thereof, polyoxyalkylene glycols, olefin compounds having an average polymerization degree of 10 to 500, higher fatty acid amides, and silicones. Of these, higher fatty acid amides are particularly preferred. As specific examples, stearylamide and ethylenebisstearylamide are preferred.
(4) Laser welding polyoxymethylene resin composition The method for producing the laser welding polyoxymethylene resin composition of the present invention is produced by melt kneading each component using a commonly used melt kneader. can do. Examples of the melt kneader include a kneader, a roll mill, a single screw extruder, a twin screw extruder, and a multi screw extruder. The processing temperature at this time is preferably 170 to 260 ° C., and in order to maintain the quality and working environment, it is preferable to perform deaeration by substitution with an inert gas or single-stage and multistage vents.
(5) About laser beam In this invention, when the wavelength of a laser beam is 700-1200 nm, it produces from the resin composition formed by mix | blending 0.001-5 weight part of (A) colorants with respect to 100 weight part of polyoxymethylene resins. It is assumed that the laser beam transmittance measured with a molded product having a thickness of 3 mm is 15% or more. That is, a laser beam having a wavelength of 700 to 1200 nm is irradiated to a molded product prepared from a resin composition in which 0.001 to 5 parts by weight of the colorant (A) is blended with 100 parts by weight of the polyoxymethylene resin The laser beam transmittance of a molded product having a thickness of 3 mm is assumed to be 15% or more. The laser beam transmittance is 15% or more, and preferably 20% or more. In the present invention, the transmittance of the laser beam need not be 15% or more in all regions of 700 to 1200 nm, and may be 15% or more in any region.

  The reason why the wavelength of the laser beam was set to 700 to 1200 nm was that this region was formed from a resin composition comprising 0.001 to 5 parts by weight of the colorant (A) with respect to 100 parts by weight of the polyoxymethylene resin. This is because the laser beam transmittance of the product is good.

The thus obtained polyoxymethylene resin composition for laser welding of the present invention can be molded by methods such as injection molding, extrusion molding, press molding, heat-pressure molding, stamping molding, and the like.
The thickness of the molded product is not particularly limited as long as laser welding can be performed at the laser welding portion. Since the molded product thus obtained has excellent laser beam transmittance, it can not only exhibit extremely excellent performance as a laser beam transmission side molded product in laser welding, but also can impart excellent design properties by blending a colorant. Therefore, it is extremely practical.

  Next, the present invention will be described with reference to examples and comparative examples. In the molded product of the polyoxymethylene resin composition shown in the examples and comparative examples, the transmittance and the tensile strength of the molded product subjected to laser welding were measured as follows.

injection molding:
Using an injection molding machine having a clamping pressure of 60 tons, a cylinder temperature of 200 ° C., a mold temperature of 80 ° C., and an injection / cooling time = 15/15 seconds were set, and an 80 × 80 × 3 mmt square plate test piece was Injection molded. About the laser beam transmittance | permeability evaluation test piece, it cut | disconnected from the sprue, the runner, and the gate, and obtained the laser beam transmittance | permeability evaluation test piece.

Evaluation of laser beam transmission:
For the evaluation of laser beam transmission, an ultraviolet near infrared spectrophotometer (UV-310, Shimadzu Corporation) was used. An integrating sphere was used as the detector. The transmittance of the molded plate from 0 to 1200 nm was measured. Among them, Table 1 shows the transmittance of each material in a light source having a laser wavelength of 940 nm (transmittance when the thickness of the molded product is 3 mm).

Creating laser welding specimens:
About the laser welding test piece, the 80 × 80 × 3 mmt square plate test piece prepared by the above-described injection molding was cut to have a width of 24 mm and a length of 70 mm to obtain a laser welding test piece. . As the laser beam transmission side material, the polyoxymethylene resin composition of the present invention is used, and as the laser beam absorption side material, a material obtained by adding 0.83 part of carbon black to 100 parts by weight of the polyoxymethylene resin is used. used.

Laser welding evaluation:
For laser welding, use Leister's MODULAS C (near infrared with a laser beam wavelength of 940 nm, maximum output is 35 W, focal length L is 38 mm, focal diameter D is 0.6 mm). evaluated. The laser beam output was unified to 30 W, and the laser beam scanning speed was unified to 6 mm / sec. Table 1 shows the welding characteristics as ● when melting marks are seen on the light incident surface of the laser beam transmitting side material, ○ when welding marks are possible without any melting marks, and x when welding is impossible. Described.

Laser welding method:
The laser beam transmitting side material was placed on the upper side and the laser beam absorbing side material was placed on the lower side. Laser irradiation was performed along the laser welding trajectory.

  The test piece for measuring the laser welding strength was a laser welding test piece, a laser beam transmission side sample and a laser beam absorption side sample, with a superposition length L of 30 mm, a welding distance of 20 mm, and superposed and welded at the welding part. Is.

Weld strength measurement:
For the measurement of the welding strength, a general tensile testing machine (AG-500B) was used, both ends of the test piece were fixed, and a tensile test was performed so that a tensile shear stress was generated at the welding site. The tensile speed during strength measurement is 1 mm / min, and the span is 40 mm. The welding strength was the stress when the welded site was broken.

Production of polyoxymethylene resin:
A triaxial (25 kg / h), 1,3-dioxolane (810 g / h), trioxane (100 mmφ, cylinder length (L) / cylinder diameter (D) = 10.2) Then, 110 ppm of boron trifluoride / diethyl etherate (2.5% benzene solution) was supplied as a catalyst, and 700 ppm of methylal was supplied as a molecular weight regulator, and continuous polymerization was performed. The polymerization was performed by controlling the outer jacket at 60 ° C. and rotating at 50 rpm. Methylal was dissolved in trioxane. Further, a premixing zone was provided so that 1,3-dioxolane and the catalyst solution were premixed immediately before being supplied to the polymerization machine. The polymer was obtained as a white fine powder at 23.0 kg / h. 9.0 g of “Sanol” LS765 [Sankyo Pharmaceutical, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate] was dissolved in 50 ml of benzene per 5 kg of the fine powder thus obtained. The solution was added and stirred for 3 minutes in a Henschel mixer to deactivate the catalyst.

  Furthermore, an antioxidant, a crude polymer decomposition aid, and a scavenger for formaldehyde generated by decomposition were added to 100 parts by weight of the crude polymer obtained by deactivating the polymerization catalyst, and a vented twin screw extruder was used. A polyoxymethylene resin was obtained by heating and kneading in a temperature range of 170 to 260 ° C.

(A) Colorant:
(A-1) monoazo orange organic pigment (Pigment Orange 64), (A-2) disazo yellow organic pigment (Pigment Yellow 128), (A-3) heterocyclic yellow organic pigment (Pigment Yellow 138), ( A-4) Phthalocyanine green organic pigment (Pigment Blue 15: 3), (A-5) Quinacridone red organic pigment (Pigment Red 122), (A-6) Perylene red organic pigment (Pigment Red 178), ( A-7) Diketopyrrolopyle red organic pigment (Pigment Red 254), (A-8) Isoindolinone yellow organic pigment (Pigment Yellow 110), (A-9) Titanium yellow (Pigment Brown 24), (A -10) Pigment Blue 29, (A-11) Complex oxide inorganic pigment (Pigment Green 50), (A-12) Titanium oxide (Pigment White 6), (A-13) Iron oxide (Pigment Red) 101).

Examples 1-10, Comparative Examples 1-5
Production of polyoxymethylene resin composition for laser welding:
In the polyoxymethylene resin composition obtained by the above method, (A) a colorant is blended at a ratio as shown in Table 1, and a temperature range of 170 to 260 ° C. using a vented twin screw extruder. Heat-kneaded. The obtained polyoxymethylene resin composition was extruded into a strand shape and pelletized with a cutter. The pellets were dried in a hot air circulating oven at 80 ° C. for 5 hours. After drying, injection molding was performed by the above-described method, and laser beam transmittance and tensile strength (welding strength) were measured. The measurement results are shown in Table 1.

From the results in Table 1, the following matters are clear.
(1) Even when various color pigments shown in Table 1 were mixed with polyoxymethylene resin, the laser beam transmittance was not significantly reduced, and a material having good laser beam transmittance was obtained. Moreover, welding could be carried out without any problem, and the welding strength was also excellent (Examples 1 to 10).
(2) As shown in Table 1, when the blending amount of the color pigment was less than 0.001 part, uneven color occurred in the molded product, and appearance characteristics were impaired. Further, regarding the welding, it was possible to confirm melting marks formed by partially decomposing the resin on the laser beam incident surface (Comparative Example 1). On the other hand, as shown in Table 1, when the blending amount of the color pigment exceeds 5 parts by weight, the laser beam permeability was deteriorated, so that the welding characteristics were impaired and the welding strength could not be measured (Comparative Example 2).
(3) When a color pigment as shown in Table 1 was used, the laser beam transmittance was deteriorated, so that the welding characteristics were impaired, and the welding strength could not be measured (Comparative Examples 3 to 5).

Claims (2)

A polyoxymethylene resin composition for laser welding obtained by blending 0.001 to 5 parts by weight of the colorant (A) with respect to 100 parts by weight of the polyoxymethylene resin, and the wavelength of the laser beam is 700 to 1200 nm. A laser-welded polyoxymethylene resin composition having a laser beam transmittance of 15% or more measured with a molded product having a thickness of 3 mm produced from the composition. (A) The colorant contains at least one pigment selected from monoazo, disazo, heterocyclic, phthalocyanine, quinacridone, perylene, diketopyrrolopyrrole, isoindolinone, titanium yellow, and ultramarine blue. The polyoxymethylene resin composition for laser welding according to claim 1.