Laser-welded objects, methods for making laser-welded objects, and compositions used therein

Abstract

The invention relates to laser welding of objects, to a laser transmission welding method, and to a laser transparent polymer composition used therein, comprising at least a combination of: (A) a polybutylene terephthalate resin (PBT resin); and (B) a dialkali metal salt of norbornane-2,3-dicarboxylic acid, or a substituted derivative thereof; and / or a polyester copolymer comprising repeating units derived from the dialkali metal salt or substituted derivative thereof incorporated into the PBT resin (referred to as A / B copolymer).

Description

Technical Field

[0001] This invention relates to a laser-welded object, a method for preparing the laser-welded object, and a polymer composition for use in molded parts for laser welding. More specifically, the invention relates to a laser-welded object obtainable by laser transmission welding, a method for preparing the laser-welded object by laser transmission welding, and a laser-transparent polymer composition. The invention further relates to a method for preparing the laser-transparent polymer composition, a method for preparing a laser-transparent molded part, the use of the laser-transparent molded part in a laser transmission welding method, and the use of the laser-welded object. The laser-transparent polymer composition in the laser-welded object according to the invention comprises at least one polyester resin, more particularly polybutylene terephthalate resin. Background Technology

[0002] Various processes exist for welding molded plastic parts, such as hot plate welding, vibration welding, and laser welding, more specifically, laser transmission welding. Laser transmission welding is a method that provides an alternative to other welding techniques, such as vibration welding and hot plate welding, and its use has seen a continuous increase in recent years, particularly with the use of diode lasers, as lasers in the near-IR wavelength region are primarily used. Laser-weldable polyester compositions are known from the prior art and described in various patents or patent applications.

[0003] Laser transmission welding is described in further detail, for example, in US 2011 / 0288220 A1. This method requires a molded plastic part exhibiting transparency to the laser wavelength, and a molded plastic part exhibiting laser absorbance. The laser-welded component itself, as well as the laser-transparent polymer composition used in the laser transmission welding process, are known. For example, laser-transparent components and laser-transparent polymer compositions comprising polyester resins used therein are described in US 2011 / 0288220 A1 and US 2008 / 0153957 A1.

[0004] According to US 2011 / 0288220 A1, polyesters, and particularly polybutylene terephthalate (PBT), are materials with several favorable properties for a variety of applications, but exhibit particularly low laser transparency and high levels of beam bulging due to their semi-crystalline morphology. For this reason, PBT and other polyesters have been used relatively infrequently as materials for laser-welded parts, although other aspects of their characteristic curves (e.g., good dimensional stability and low water absorption) make them very attractive for this type of application. Also according to US 2011 / 0288220 A1, rapidly crystallizing materials (such as PBT) also offer processing advantages, particularly rapid demolding and therefore short cycle times. Therefore, it is desirable to combine semi-crystalline properties with rapid crystallization and high laser transparency. Although various attempts have been made to improve the laser transparency of polyesters, the effects achieved using those reported in US 2011 / 0288220 A1 have generally been relatively small and therefore not entirely satisfactory, or have exhibited other serious drawbacks, such as achieving increased laser transparency at the expense of mechanical properties.

[0005] US 2011 / 0288220 A1 discloses and reports thermoplastic molding compositions suitable for the production of laser-transparent molded articles, comprising, in addition to polyester resin, 0.05 wt.% to 2.0 wt.% of Na₂CO₃, K₂CO₃, NaHCO₃, KHCO₃, or mixtures thereof as a basic component. These compositions exhibit significant laser transparency, preferably at least 33% (measured at 1064 nm on a molded article with a thickness of 2 mm).

[0006] However, a drawback of these compositions is that the increased laser transparency comes at the cost of mechanical properties. In other words, these compositions also exhibit a loss of mechanical properties compared to corresponding compositions that do not contain the necessary components. This is seen in the reduced impact resistance of the unreinforced formulation accompanied by significantly lower fracture strain, and in the reduced impact resistance of the reinforced formulation accompanied by slightly lower fracture strain.

[0007] Other laser-weldable polyester compositions are described, for example, in US 2008 / 0153957 A1. The composition of US 2008 / 0153957 A1 comprises (A) polybutylene terephthalate (PBT) resin and (B) a fatty acid compound in an amount ranging from 0.01 to 1.0 parts by weight (pbw), preferably from about 0.03 to 0.5 pbw, relative to 100 pbw of PBT resin. The fatty acid compound is suitably a fatty acid ester, a fatty acid amide, or a metal salt of a C12-36 fatty acid. The metal salt of a C12-36 fatty acid may, for example, include alone or in combination alkali metal salts (e.g., sodium and potassium salts), alkaline earth metal salts (e.g., magnesium and calcium salts), salts of Group 2B metals of the periodic table (e.g., zinc salts), and salts of Group 3B metals of the periodic table (e.g., aluminum salts). According to US 2008 / 0153957 A1, adding fatty acid series compounds to the resin composition in the specific low proportions described above effectively ensures improved laser transmittance, while the improvement is insufficient with lower proportions of fatty acid series compounds, and on the other hand, there is a possibility of laser transmittance degradation with higher proportions of fatty acid series compounds. The composition of US 2008 / 0153957 A1 may contain other components, such as fibers and fillers, as well as other auxiliary additives for PBT-based polyester compositions. However, in the embodiments of US 2008 / 0153957 A1, component (B) shows a modest effect on transparency.

[0008] For laser transmission welding, it is crucial that the laser-transparent polymer composition exhibits sufficient laser transparency, as well as adequate mechanical properties. Insufficient laser transparency can result in undesirable defects such as insufficient weld strength and / or burn marks. It is generally known that the physical properties of a polymer (such as glass transition temperature and melt temperature, viscosity, etc.) and mechanical properties (such as toughness) depend on the polymer's molecular weight. The lower the molecular weight, the lower the transition temperature, viscosity, and mechanical properties will be. Therefore, maintaining the molecular weight during compounding and further processing is critical. Sufficient retention of mechanical properties can be related to maintaining the polymer's viscosity, for example, as measured by methods used to measure relative solution viscosity (RSV). Summary of the Invention

[0009] Therefore, an object of the present invention is to provide a laser-welded object comprising a laser-transparent component, and a laser welding method for preparing the laser-welded object, wherein the laser-transparent component comprises a laser-transparent polymer composition exhibiting sufficient laser transparency while possessing sufficient mechanical properties for these molded articles and improved polyester RSV retention. Another object of the present invention is to provide a laser-transparent polymer composition and molded articles made therefrom, which exhibit sufficient laser transparency with sufficient mechanical properties and improved RSV retention.

[0010] Surprisingly, these objectives have been achieved using various embodiments of the invention, which relate to laser-welded objects, laser-transparent polymer compositions, laser-transparent molded parts made therefrom, and methods for manufacturing them. Detailed Implementation

[0011] The laser-welded object according to the present invention comprises two molded parts (P1) and (P2) welded together by laser transmission welding, wherein

[0012] - The first molded part (P1) comprises a laser-transparent polymer composition (I); and

[0013] - The second molding part (P2) contains a laser-absorbing polymer composition (II); The laser-transparent polymer composition (I) comprises: (A) Polybutylene terephthalate resin (PBT resin); and (B) dialkali metal salts of norbornane-2,3-dicarboxylic acid, and / or their substituted derivatives; and / or - Polyester copolymers (referred to as A / B copolymers) include repeating units incorporated into PBT resins, said repeating units being derived from dialkali metal salts of norbornane-2,3-dicarboxylic acid and / or their substituted derivatives.

[0014] The present invention also relates to a laser-transparent polymer composition comprising...

[0015] (A) Polybutylene terephthalate resin (PBT resin); and

[0016] (B) dialkali metal salts of norbornane-2,3-dicarboxylic acid, and / or their substituted derivatives (component (B)). and / or - Polyester copolymers (referred to as A / B copolymers) include repeating units incorporated into PBT resins, said repeating units being derived from dialkali metal salts of norbornane-2,3-dicarboxylic acid and / or their substituted derivatives; And at least one component selected from (C) and (D), wherein (C) is glass fiber; and (D) is a colorant.

[0017] The inventors have unexpectedly discovered, based on various experiments, that polyester compositions comprising a dialkali metal salt of norbornane-2,3-dicarboxylic acid and / or its substituted derivatives, in combination with PBT resin, exhibit significantly improved laser transparency and very good retention in RSV. The laser transparency is generally greater than sufficient for use in laser welding processes. Furthermore, molded parts made from polyester compositions comprising PBT resin (component (A)) and a dialkali metal salt of norbornane-2,3-dicarboxylic acid and / or its substituted derivatives (B) exhibit good mechanical properties, as illustrated by the high elongation at break of fiber-reinforced polyester compositions containing glass fibers in addition to components (A) and (B). The following embodiments illustrate this.

[0018] The corresponding compositions according to US 2011 / 028822 A1 containing disodium carbonate (Na2CO3) instead of component (B) also showed a significant improvement in laser transparency, some even better than those containing component (B), but retention in RSV was far from good. RSV was significantly reduced, particularly at higher amounts of the additive. Furthermore, the elongation at break of fiber-reinforced polyester compositions with Na2CO3 was lower than that of the corresponding compositions containing component (B). The inventors have also tested other alkali metal salts of aliphatic monocarboxylic and dicarboxylic acids, including sodium lignite, disodium oxalate, and disodium succinate. Sodium lignite is an alkali metal salt of C12-36 fatty acids according to US 2008 / 0153957 A1. In contrast to the effect of component (B), these other additives either failed to improve laser transmission, some even reduced it, or were worse in terms of RSV and / or reduction in elongation at break, even compared to Na2CO3. For sodium lignite, a much higher amount than reported in US 2008 / 0153957 A1 is required to improve laser transmission, but this is accompanied by a significant reduction in RSV and elongation at break.

[0019] Disodium salts of PBT and norbornene-2,3-dicarboxylic acid (also known as disodium; bicyclo[2.2.1]heptane-2,3-dicarboxylic acid, or bicyclo[2.2.1]heptane-2,3-dicarboxylic acid; commercially available from Millliken as Hyperform HPN68L; CAS No. 23838-83-7) are known and described, for example, in US 2019 / 0375933 A1 and US 6465551 B1. US 2019 / 0375933 A1 describes disodium bicyclo[2.2.1]heptane-2,3-dicarboxylic acid as a nucleating agent in polyester compositions, among many other components including talc and sodium lignite. This document relates to the production of very small parts, such as those with a material volume of less than ≤1 ml, and particularly to their dimensional stability. The compositions of US 2019 / 0375933 A1 typically contain at least 0.01 wt.% and at most 2.00 wt.% of a nucleating agent, and in very high amounts in the polyester polymer, preferably ≥95 wt.%, more preferably ≥98 wt.% composed of PBT. US 2019 / 0375933 A1 makes no mention of the laser transparency of compositions containing sodium lignite and HPN68L, or any effect of these nucleating agents on the RSV of the polyester. US 2019 / 0375933 A1 also makes no recommendations regarding any filled, reinforced, or colored compositions, let alone the suitability of any such compositions for transmission laser welding processes.

[0020] US 6465551 B1 describes the use of bicyclic [2.2.1]heptane dicarboxylate as a nucleating agent for polyolefins. It is mentioned here that the use of nucleating agents is not limited to polyolefins, and can also impart beneficial nucleating properties to polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN), as well as polyamides such as nylon 6, nylon 6,6, etc. Although a general description of experiments blending nucleating agents in PET bottle-grade resins is given, no specific examples or characteristics are provided.

[0021] EP 2949703 A1 describes the use of polyester compositions for laser transmission welding applications. The compositions of EP 2949703 A1 comprise 30-100 wt.% of a first polyester (70-99.9 wt.%) and polyethylene terephthalate (PET) (0.01-30 wt.%), 0-5 wt.% of a phosphorus-containing compound, and 0-70 wt.% of additional additives. The first polyester differs from PET and is particularly PBT. To increase the laser transparency of the polyester, especially PBT, the polyester is blended with PET. For PET, PET copolymers, for example, can also be used. Modification is possible with various other monomers or their derivatives. EP 2949703 A1 mentions a long list, including norbornane-2,3-dicarboxylic acid, but does not provide further details about these other monomers, nor does it offer any comment on their effect on laser transparency. Furthermore, EP 2949703 A1 does not disclose the use of an alkaline salt of norbornene-2,3-dicarboxylic acid, or its derivatives, in polyester compositions, or its effect on the laser transparency of PBT-based compositions.

[0022] Range, laser transparency and other expressions

[0023] It should be noted that in expressions, where a range with an upper and / or lower limit is mentioned, the range explicitly includes any value within that range, as well as the mentioned upper and lower limits. For example, in "amounts in the range of 0.2–5.0 wt.%", the range explicitly includes 0.2 wt.% and 5.0 wt.% and any value between 0.2 wt.% and 5.0 wt.%.

[0024] The word "and / or" used in expressions such as "feature (a) and / or feature (b)" has the same meaning as the word "feature (a) or feature (b), or a combination of feature (a) and feature (b)," and can replace the word "feature (a) or feature (b), or a combination of feature (a) and feature (b); thus implying that either feature (a) or feature (b), or both feature (a) and / or feature (b) can be applicable. Therefore, in the laser-transparent polymer compositions according to various embodiments of the invention, comprising PBT resin (A) and a dialkali metal salt (B), and / or an A / B copolymer, the composition may contain an A / B copolymer which may coexist with components (A) and (B); or replace components (A) and (B); thus replacing part or all of components (A) and (B).

[0025] The phrase “at least one component is selected from” means that only one of the listed components is present after “at least one component is selected from”, as well as a combination of the listed components or even all the components listed after “at least one component is selected from”.

[0026] The word “one or more” used in expressions such as “one or more other components” has the same meaning as the word “one or more” and can be replaced by the word “one or more”, and “more than one” can be, for example, two, three, four, five, seven, ten, etc.

[0027] The terms “laser transparent” and “laser transparency” used herein should be understood as “laser light transparent” and “laser light transparent”, respectively.

[0028] Here, the laser-transparent polymer composition should be understood as a composition exhibiting at least 25.0% laser transparency for a laser wavelength of 980 nm, as measured on a 1 mm thick test sample according to the TMG3 method further described below (Experimental Section). Injection molding was performed using standard PBT molding conditions (Experimental Section).

[0029] Laser-transparent polymer composition

[0030] The laser-transparent polymer composition used in the laser-welded object according to the invention, and in the method for manufacturing the object, contains at least [missing information].

[0031] (A) Polybutylene terephthalate resin (PBT resin); and

[0032] (B) dialkali metal salts of norbornane-2,3-dicarboxylic acid, and / or their substituted derivatives; and / or its A / B copolymer.

[0033] The composition may further comprise other components, such as glass fibers, colorants, and / or additional components. In a particularly preferred embodiment of the composition according to the invention and the molded parts made therefrom, the composition can be used in laser-welded objects and methods for manufacturing such objects, wherein the composition comprises, in addition to components (A) and (B), at least glass fibers (component (C)), or colorants (component (D)), or combinations thereof.

[0034] A / B copolymer

[0035] Without being bound by any theory, the inventors believe that carboxylates or carbonates can react with the polymer chains of the PBT resin (component (A)). Furthermore, to explain the difference between component (B) and other carboxylic acid and carbonate components, these reactions typically lead to chain scission, resulting in a lower average molecular weight and a lower RSV. Moreover, as the inventors believe, component (B) may be able to further react and intercalate into the polymer chains of the PBT resin, thereby recovering some or most of its molecular weight and unexpectedly enabling the composition to exhibit sufficient laser transparency, better RSV retention, and adequate mechanical properties, as illustrated in the following examples.

[0036] As a result of such a reaction, the composition may also include a polyester copolymer comprising repeating units of a dialkali metal salt derived from norbornane-2,3-dicarboxylic acid and / or its substituted derivatives, which are incorporated into the PBT resin. Such repeating units may be referred to as norbornane-2,3-dicarboxylic acid ester repeating units, and such copolymers derived from PBT resins and comprising norbornane-2,3-dicarboxylic acid ester repeating units are referred to herein as A / B copolymers. When these substituted derivatives are also included in component (B), the statement "norbornane-2,3-dicarboxylic acid ester repeating unit" includes its substituted derivatives.

[0037] Therefore, the inventors anticipate that component (B) exists in the composition either on its own or in combination with the A / B copolymer, or as a combination thereof. This is reflected in the statement, as used further herein, that “component (B) exists as is and / or in combination with the A / B copolymer.”

[0038] Therefore, the amount of component (B) present in the composition (expressed in wt.% or parts by weight) should be understood herein to include the amount of any portion of component (B) incorporated into the A / B copolymer. And where the amount is expressed relative to the combined amount of components (A) and (B), the combined amount includes the A / B copolymer as it is present.

[0039] Even if component (B) can exist in the form of repeating units incorporated in the PBT resin, and is therefore part of the A / B copolymer, the molar amount of component (B) in the composition, and wt.%, can be determined by proton nuclear magnetic resonance (NMR) if subsequently determined. 1 H-NMR measurement. 1 H-NMR is also suitable for determining the ratio of the amount of component (B) present as is to the amount of component (B) present as repeating units bound to the PBT resin. This amount, if determined subsequently, can be obtained via proton nuclear magnetic resonance (NMR). 1 H-NMR measurements were performed. The experimental section describes this. 1 H-NMR.

[0040] Accordingly, the amount of component (A) present in the composition (expressed in wt.% or parts by weight) should be understood herein as the combined amount of the components in the PBT resin, and includes component (A) in any part of the A / B copolymer, while excluding any part or repeating unit derived from component (B) bound in the A / B copolymer. Therefore, the amounts of component (A) and component (B) reported below correspond to the respective amounts used to prepare the composition, which can be prepared by melt mixing, and thus without regard to any further reactions between them.

[0041] Component (A) Polyester

[0042] Component (A) in the laser-transparent polymer composition according to the invention is polybutylene terephthalate (PBT) resin. The PBT resin is suitably a PBT homopolymer or a PBT copolymer, or a combination thereof. The PBT homopolymer consists primarily of copolymer units of butene and terephthalate. Such a homopolymer can be suitably prepared by copolymerization of butanediol and terephthalic acid, wherein these monomers are used as the sole monomers. The PBT homopolymer may contain other copolymer units resulting from trace amounts of other components; for example, trace impurities in butanediol and / or terephthalic acid, or trace impurities formed during the polycondensation of butanediol and terephthalic acid. Suitably, the PBT homopolymer consists of at least 99 mol% of butene units and terephthalate units, and at most 1 mol% of other copolymer units, relative to the total molar amount of butene units, terephthalate units, and other copolymer units.

[0043] Component (A) may comprise or consist of a PBT copolymer. This PBT copolymer differs from the A / B copolymers mentioned above because it does not contain repeating units derived from norbornane-2,3-dicarboxylic acid, or substituted derivatives, or their alkali metal salts. The PBT copolymer of component (A) may comprise other comonomers, and these comonomers may copolymerize in small amounts into copolymer chains. Examples of such other comonomers include bifunctional monomers, i.e., monomers having two reactive sites, such as other diacids (e.g., isophthalic acid), other diols (e.g., ethylene glycol), and functional comonomers (e.g., sodium 5-sulfoisophthalate). If present, the bifunctional comonomer is suitable to be present in amounts up to about 10 mol% or up to about 5 mol%. Comonomers having more than two reactive sites, such as trimellitic anhydride, trimellitic acid, pyromellitic dianhydride (PMDA), and pentaerythritol, may suitably be incorporated as branching agents to increase melt viscosity. If present, such comonomers having more than two reactive sites are suitably present in amounts up to about 5 mol%, or even better, up to about 2.0 mol%. Suitablely, the PBT copolymer comprises at least about 85 mol% of comonomers of butene (butene units) and terephthalate (terephthalate units) and up to about 15 mol% of comonomers of other comonomers (comonomer units). Examples of other comonomers that can be copolymerized into PBT copolymers include, for example, isophthalic acid, propylene glycol, and butanediol. Preferably, the PBT copolymer comprises at least about 90 mol%, more preferably at least about 95 mol%, or even more preferably at least about 98 mol% of butene units and terephthalate units; and correspondingly preferably at most about 10 mol%, more preferably at most about 5 mol%, or even more preferably at most about 2.0 mol% of comonomer units. In this document, the molar percentages (mol%) of butene units, terephthalate units, and comonomer units are all relative to the total molar amount of butene units, terephthalate units, and comonomer units in the copolymer.

[0044] In a preferred embodiment, the PBT resin (component (A)) in the laser-transparent polymer composition is a PBT homopolymer, or a PBT copolymer comprising at least 98 mol% of butene and terephthalate copolymer units and at most about 2.0 mol% of comonomer copolymer units, relative to the total molar amount of butene units, terephthalate units and comonomer units in the copolymer.

[0045] The polybutylene terephthalate resin (component (A)) used to prepare the compositions according to the invention can be any polybutylene terephthalate resin commonly used to prepare thermoplastic polyester molding compositions. The resin can have correspondingly varying properties, such as viscosity and melt flow ratio. Suitably, the polybutylene terephthalate resin has a relative solution viscosity (RSV) as high as about 2.8, or even higher, or as low as about 1.5, or even lower than 1.5. Preferably, the PBT resin has an RSV in the range of 1.8-2.6, more preferably in the range of 1.9-2.3. In this document, the relative solution viscosity (RSV) is measured according to the method of ISO 307 at 25°C in 100 g of m-cresol at a concentration of 1 g.

[0046] The advantage of PBT resins with lower viscosity is that laser-transparent polymer compositions exhibit improved processing behavior, while the advantage of higher viscosity is that molded parts made from the composition have better mechanical properties. The advantage of PBT resins with viscosity within a preferred range is that the composition combines good processing behavior and good mechanical properties. The advantage of PBT resins with viscosity within a more preferred range is that the composition achieves an even better balance between processing behavior and mechanical properties.

[0047] Suitably, the laser-transparent polymer composition comprises at least 35 wt.% of component (A), wherein the weight percentage (wt.%) is relative to the total weight of the composition. The amount of component (A) relative to the total weight of the composition can be up to 99.8 wt.%. This amount relative to the total weight of the composition can be, for example, as low as or about 40 wt.%, 45 wt.%, 50 wt.%, 55 wt.%, or 58 wt.%, or as high as or about 99.5 wt.%, 99 wt.%, 98 wt.%, 95 wt.%, 90 wt.%, 80 wt.%, 75 wt.%, or 70 wt.%.

[0048] Suitably, the amount of component (A) is in the range of 35-99.8 wt.% or a subrange thereof. For example, the amount of component (A) relative to the total weight of the composition is in the range of 35-90 wt.%, more specifically 40-85 wt.%. This range is particularly preferred for embodiments in which the composition further comprises at least glass fiber (component (C)).

[0049] Alternatively, the amount of component (A) relative to the total weight of the laser-transparent polymer composition is in the range of 85-99.8 wt.%, more specifically 90-99.5 wt.%. This range is particularly preferred for embodiments in which the composition further comprises at least one colorant (component (D)).

[0050] Component (B) Dialkali metal salt

[0051] The laser-transparent polymer compositions according to various embodiments of the present invention comprise a dialkali metal salt of norbornane-2,3-dicarboxylic acid and / or its substituted derivatives (component (B)). Norbornane-2,3-dicarboxylic acid is a compound having a bicyclic structure comprising 7 carbon atoms with two carboxylic acid groups, each at positions 2 and 3, and 10 hydrogen atoms, each at positions 1, 2, 3, and 6, and each at positions 4, 5, and 7. In the substituted derivatives of the dialkali metal salt of norbornane-2,3-dicarboxylic acid, one or more hydrogen atoms may be substituted by substituents. Substituents may be single or multiple, at any of the 1-7 positions: 1, 2, 3, and 6; single 4, 5, and 7; single or double; and any combination thereof. Substituents may be selected from the group consisting of alkyl, aryl (e.g., phenyl), alkylphenyl groups, hydroxyl groups, amines, halogens, alkoxy groups, enoyl groups, alkylamines, and carbocyclic groups. Preferably, the substituted derivative contains one or more alkyl groups as substituents, more preferably one or more methyl groups, and even more preferably one or two methyl groups. Most preferably, the dialkali metal salt is the dialkali metal salt of norbornene-2,3-dicarboxylic acid; that is, in its unsubstituted form having hydrogen at all positions except the two carboxyl groups.

[0052] In the dialkali metal salts of norbornane-2,3-dicarboxylic acid and / or their substituted derivatives, the alkali metal can be any alkali metal and is suitably selected from the group consisting of lithium, sodium, and potassium, or any combination thereof. Preferably, the alkali metal comprises sodium or potassium, or a combination thereof, more preferably sodium, or even sodium. Preferably, the dialkali metal salt comprises a disodium salt, and most preferably, the alkali metal salt is composed of disodium norbornane-2,3-dicarboxylic acid.

[0053] Component (B) is suitably present in an amount ranging from 0.2 to 6.0 parts by weight (pbw), preferably 0.3 to 5.0 pbw, and more preferably 0.4 to 4.0 pbw, relative to 100 pbw of components (A) and (B). The amount of component (B) is also suitably in the range of 0.2 to 5.0 wt.%, preferably 0.25 to 4.0 wt.%, and more preferably 0.3 to 3.0 wt.%, relative to the total weight of the composition. Here, component (B) may be present as is and / or incorporated into the A / B copolymer as described above, and the combined amount of components (A) and (B) includes, if present, the A / B copolymer. Higher amounts of component (B) are advantageous for higher laser transparency, while lower amounts have the advantage of even better retention of the RSV of the polyester. The preferred range provides an optimal combination of high laser transparency and good retention of the RSV of the polyester.

[0054] Component (C) Glass fiber

[0055] The compositions according to various embodiments of the invention may be unreinforced, i.e., not containing a reinforcing agent, or may be reinforced, i.e., containing a reinforcing agent, such as glass fiber or glass sheet. In a preferred embodiment of the composition according to the invention, the composition contains glass fiber (component (C)).

[0056] For the glass fiber (component (C), any glass fiber suitable for fiber reinforcement polyester composition and molding method for manufacturing fiber-reinforced molded parts from such composition can be used. Suitable glass fibers are known in the art. The glass fibers used to prepare the fiber-reinforced laser-transparent polymer composition according to the invention can have lengths varying over a wide range. These can be used in the form of rovings or in the form of commercially available chopped glass. The glass fibers can be added as continuous fibers or as cut or ground glass fibers, and it is possible to equip the fibers with suitable sizing systems and adhesion promoters or adhesion promoter systems, such as silane-based ones. Particularly preferred here are glass fibers in the form of E-glass (alumina borosilicate glass with less than 1 wt.% alkali metal oxide, mainly used for glass-reinforced plastics), but other types of glass fibers, such as A-glass (soda lime glass with little or no boron oxide), E-CR glass (with less than 1 wt.% alkali metal oxide), can also be used. Aluminosilicate glass with wt.% alkali oxides, exhibiting high acid resistance, C-glass (e.g., soda lime glass with high boron oxide content for use in glass short fibers), D-glass (borosilicate glass with high dielectric constant), R-glass (aluminosilicate glass without MgO and CaO, exhibiting high mechanical requirements), and S-glass (aluminosilicate glass without CaO but with high MgO content and high tensile strength).

[0057] In this document, a fiber is understood as a material composed of particles having a three-dimensional elongated body having a length (L), a diameter (D), and a thickness (T), and having an aspect ratio (L / D) defined as at least 10 of its length (L) divided by its diameter (D). In this document, the elongated body has a cross-section perpendicular to its length, defined by its diameter (D) and thickness (T). This cross-section can be circular or non-circular. In the case of a non-circular cross-section, the diameter (D) is the maximum dimension of the cross-section, and the thickness (T) is the minimum dimension of the cross-section. In the case of a circular cross-section, the diameter (D) and thickness (T) are equal.

[0058] Suitablely, these glass fibers have a median aspect ratio (L / D) of at least 15:1, preferably at least 20:1. The glass fibers suitably have a fiber diameter between 3 and 20 μm (micrometers). The glass fibers can have cross-sectional shapes of different shapes. The glass fibers suitably have a circular cross-section. These glass fibers can have a number-average diameter, for example, about 7 µm, about 8 µm, or about 9 µm, or about 10 µm, or about 12 µm, or about 15 µm. Preferably, the number-average diameter is in the range of 8-15 µm, more preferably in the range of 9-12 µm. The glass fibers can also have a non-circular cross-section, such as an elliptical cross-section or an elliptical cross-section. A non-circular cross-section is characterized by a cross-section with different diameters in different directions. Suitablely, glass fibers with non-circular cross-sections have a maximum diameter, for example, about 5 µm, or about 8 µm, or about 9 µm, or about 10 µm, or about 12 µm, or about 15 µm, or about 18 µm. Preferably, the average value of the maximum diameter is in the range of 9-18 µm, more preferably in the range of 10-15 µm.

[0059] In preferred embodiments of the laser-transparent polymer composition, the glass fiber (component (C)) can be present in a wide range of amounts. This amount can be, for example, as low as or about 15 wt.%, 10 wt.%, or 5 wt.% or even lower; or as high as or about 30 wt.%, 35 wt.%, 40 wt.%, 45 wt.%, 50 wt.%, or even higher relative to the total weight of the composition. Preferably, the laser-transparent polymer composition according to these embodiments comprises component (C) in an amount ranging from 5 to 50 wt.%, more preferably from 10 to 45 wt.%, and even more preferably from 15 to 40 wt.% relative to the total weight of the composition.

[0060] Component (C), i.e., glass fiber, if used, is suitably present in an amount in the range of 10-100 pbw relative to a combined amount of 100 pbw of components (A) and (B). Preferably, the amount of component (C) is in the range of 20-80 pbw, more preferably 30-70 pbw, and even more preferably 35-60 pbw, relative to a combined amount of 100 pbw of components (A) and (B). Higher minimum amounts of component (C) have the advantage of better mechanical properties of the composition, specifically higher tensile strength. Lower maximum amounts of component (C) have the advantage of better laser transparency of the composition.

[0061] Component (D) Colorant

[0062] The compositions according to different embodiments of the invention may be neutral in color, i.e., not containing a colorant, or may be colored, i.e., containing a colorant, such as a pigment or dye. In a preferred embodiment of the composition according to the invention, the composition contains a colorant (component (D)).

[0063] Organic and inorganic pigments and / or dyes are suitable as colorants. Inorganic pigments such as titanium dioxide, ultramarine, iron oxide, and carbon black; in addition, organic pigments such as phthalocyanine, quinacridone, dinaphthalene, and dyes such as aniline black and anthraquinone can be used as colorants, and other colorants can be added if these do not absorb within the range of the laser used. Alternatively, they can be used in such small amounts that at least partial transmission of the laser is still possible. Colorants such as soot and carbon black can, but preferably only in very small amounts: preferably less than 0.1 wt.%, more preferably less than 0.05 wt.%, or even less than 0.02 wt.%, or 0.01 wt.%, relative to the total weight of the composition.

[0064] Examples of inorganic pigments include antimony trioxide, antimony pentoxide, basic lead carbonate, basic lead sulfate or lead silicate, zinc barium white, titanium dioxide (anatase, rutile), zinc oxide, zinc sulfide, metal oxides such as Berlin blue, lead chromate, lead sulfochromate, antimony chromium titanate, chromium oxide, iron oxide, cobalt blue, cobalt chromium blue, cobalt nickel gray, manganese blue, manganese violet, molybdate orange, molybdate red, antimony nickel titanate, and ultramarine, metal sulfides such as antimony trisulfide, cadmium sulfide, cadmium sulfonate selenide, zirconium silicate, zirconium vanadium blue, and zirconium praseodymium yellow.

[0065] Examples of organic pigments include anthrone, azo, azomethyl, benzoanthrone, quinacridone, quinophthalone, dioxazine, flavanone, indanone, isoindoline, isoindolineone, methyl alkaloid, violetone, perylene, phthalocyanine, pinanthrone, pyrrolo-pyrrole, thioindigo pigments, and, for example, metal complexes. Metal salts of azo, azomethyl, methylene dyes or azo compounds, azomethyl or methylene dyes, azomethyl, quinacridone, dioxazine, isoindoline, isoindolineone, dinaphthalene, phthalocyanine, pyrrolopyrrole and indigo sulfide colorants, as well as bismuth vanadate, anthraquinone series such as alkylamino, amino, arylamino, cyclohexylamino, hydroxy, hydroxyamino or phenylthio-anthraquinone, triphenylmethane dyes, and fluorescent dyes such as those from benzothiazole, coumarin, oxacyanine or thiazine series, pyrazolone, violaceone and anthraquinone methylene, azo and coumarin types.

[0066] In a specific embodiment, the laser-transparent polymer composition according to the present invention comprises a laser-transparent colorant. Hereinafter, a laser-transparent colorant is understood to be a colorant that absorbs light with wavelengths less than 800 nm in the visible light region and transmits light with wavelengths from 800 nm to 1200 nm in the infrared region.

[0067] Suitably, the composition comprises an amount of the laser-transparent colorant in the range of 0.01-5 wt.%, 0.1-3 wt.%, preferably 0.2-2.0 wt.%, and more preferably 0.3-1.5 wt.% relative to the total weight of the composition.

[0068] The laser-transparent colorant in this invention can be any color, or a combination of different colors. Suitablely, the laser-transparent colorant is a black colorant or a non-black colorant, or any combination thereof. Non-black laser-transparent colorants can have any color, such as red, yellow, green, blue, or purple.

[0069] In a preferred embodiment of the invention, the laser-transparent polymer composition comprises a single black laser-transparent colorant, or a combination of a black laser-transparent colorant and at least one non-black laser-transparent colorant, or a combination of at least two non-black laser-transparent colorants providing black. Such a combination of at least two non-black laser-transparent colorants providing black is also referred to herein as a "black coloring combination".

[0070] Black is understood here as having an L value of up to 35, as measured according to the method of ISO 7724-1-2-3. The color value. Therefore, "black-coloring combination" with colorants is understood herein to mean a combination of colorants providing a composition comprising said colorant combination, the color having an L value of up to 35 as measured by method according to ISO 7724-1-2-3. value.

[0071] More preferably, the composition comprises a black coloring combination of two or more different non-black laser-transparent colorants. The advantage of a composition comprising a black-coloring combination of two or more different non-black interposer-light-transparent colorants is that it can produce molded parts with a black impression (compared to soot coloring) and very good surface quality. This composition maintains high laser transparency within the range of non-coloring materials and is suitable for many welding applications requiring dark or black parts.

[0072] This black-coloring combination suitably comprises a mixture of colorants with different colors (i.e., absorption at different wavelengths in the visible region below 800 nm). Numerous embodiments exist of combinations of mixed colorants that can be used to produce the black-coloring combination. For example, embodiments of dyes that can be used as non-black laser-transparent colorants in such combinations are described in EP 1240243A1. Typically, dyes exhibiting blue, purple, and green can be the main components in producing black dyes. Examples include combinations of blue, red, and yellow dyes; combinations of green, red, and yellow dyes; combinations of blue, green, red, and yellow dyes; and combinations of green, purple, and yellow dyes. Examples include combinations of dyes selected from pyrazolinones; violet ketones; anthraquinones, such as anthraquinone green, anthraquinone blue, or anthraquinone purple dyes; methylene, azo, and coumarin types; metal-containing pigments, such as inorganic pigments; metal complexes of the azo, azomethyl, or methylene dye, azomethyl, quinacridone, dioxazine, isoindoline, isoindoline, perylene, phthalocyanine, pyrrolopyrrole, and thioindigo types; quinoline ketone dyes; and metal azo. More specifically, neutral anthraquinone dyes imparting blue, purple, or green hues can be used as the main component of the resulting black coloring combination by mixing with red and then yellow dyes. Dyes belonging to monoazo complex dyes can be mixed with anthraquinone dyes to produce a black dye used as a colorant in the composition. In other black coloring combinations, the colorant / amine salt of the anthraquinone dye can be combined with a second dye selected from the group consisting of violet ketone dyes, monoazo complex dyes, anthraquinone pyridone dyes, and anthraquinone dyes.

[0073] Suitably, the composition comprises a black coloring combination of at least two laser-transparent colorants in a total amount ranging from 0.1 to 3 wt.%, preferably 0.2 to 2.0 wt.%, more preferably 0.3 to 1.5 wt.%, relative to the total weight of the composition.

[0074] In a preferred embodiment, the composition comprising a black-coloring combination of at least two non-black laser-transmitting colorants has a transmittance of at least 10% in the spectral subrange of the VIS spectral range (400-700 nm wavelength range).

[0075] In another preferred embodiment of the invention, the laser-transparent polymer composition has an L content of up to 35, preferably up to 33, more preferably up to 32. A black composition with a value of L. Here, the color parameter L is measured according to the method of ISO 7724-1-2-3. The value of L. For a perfect black material, the lower limit of L is 0, and preferably, L is at least 5.

[0076] In a particularly preferred embodiment, the composition according to the invention is a black composition having a transparency of at least 25.0%, preferably at least 30.0%, more specifically at least 35.0%, and even more specifically at least 40%, measured at a thickness of 1.0 mm and a wavelength of 980 nm by a method according to TMG3, further described herein. Even more preferably, the composition further has a transparency of at least 15.0%, more specifically at least 17.5%, and even more specifically at least 20.0%, measured at a thickness of 2.0 mm and a wavelength of 980 nm by a method according to TMG3, further described herein. Here, the transparency measurements are performed on injection-molded substrates having thicknesses of 1.0 mm and 2.0 mm, respectively.

[0077] At wavelengths in the approximately 400-700 nm range, the transmittance of the composition in the visible region (VR) can vary over a wide range and can be as high as in NIR, but also much lower, depending on the presence of other additives.

[0078] Component (E) Other Components

[0079] The laser-transparent polymer compositions comprising components (A) and (B) used in this invention, and specific embodiments comprising components (C) and / or (D), may optionally contain one or more other components, or other additives. These one or more other components are collectively referred to herein as component (E). These one or more additional components may be any auxiliary additives, or combinations of auxiliary additives, used in polyester compositions. Examples include particulate fillers, such as glass beads, amorphous silica, asbestos, calcium silicate, calcium metasilicate, magnesium carbonate, kaolin, chalk, powdered quartz, mica, barium sulfate, and feldspar; other fibers, i.e., fibers other than glass fibers, such as aramid fibers and potassium titanate fibers; processing aids; stabilizers, such as heat stabilizers, light stabilizers, and antioxidants; lubricants and release agents; and plasticizers, etc.

[0080] During the preparation of the composition, one or more additives may be added at any desired stage by any suitable conventional method. In this document, additives may be added, for example, alone, or as a premix with one or more other components, or as a masterbatch. Suitablely, one or more additives are added as a masterbatch, including one or more additives dispersed in the PBT resin.

[0081] One or more additional additives of component (E) are preferably used in amounts such that these additives do not affect or impair the laser transparency and / or mechanical properties of the composition, or only to a limited extent. Suitably, component (E) is present in the laser-transparent polymer composition, if any, in an amount of up to 20 wt.%, preferably up to 15 wt.%, and most preferably in the range of 0-10 wt.%, relative to the total weight of the composition. If not used at all, particulate filler is suitably present in an amount of up to 15 wt.%, preferably up to 10 wt.%, and more preferably 0-5 wt.%, relative to the total weight of the composition. Other fibers (i.e., fibers other than glass fibers, if used) are also suitably present in an amount of up to 15 wt.%, preferably up to 10 wt.%, and more preferably 0-5 wt.%, relative to the total weight of the composition. Suitably, the other fibers have a median aspect ratio of at least 15:1, preferably at least 20:1, and / or a fiber diameter between 3 and 20 µm (micrometers).

[0082] The filler herein should be understood as a particulate material consisting of particles having a three-dimensional shape defined by length (L), diameter (D), and thickness (T) and having an aspect ratio (length / diameter) of less than 10:1. Here, length (L) is the largest in the three dimensions, and thickness (T) is the smallest in the three dimensions, and diameter (D) can be between, equal to, or equal to length (L) and thickness (T), or, in the case of spherical particles, equal to both length (L) and thickness (T). Suitably, the particulate material has a median aspect ratio of about 5:1 or less.

[0083] Preferably, the combined amount of particulate filler and other fibers, relative to the total weight of the composition, is in the range of 0-15 wt.%, even more preferably 0-10 wt.%, and most preferably 0-5 wt.%. Furthermore, the fibers and fillers with high laser absorption (e.g., carbon fibers, graphite, graphene, or carbon nanotubes) are preferably present in an amount of less than 1 wt.%, more preferably in an amount in the range of 0-0.25 wt.%, and particularly preferably in an amount in the range of 0-0.05 wt.%, relative to the total weight of the composition.

[0084] Examples of compositions according to the present invention

[0085] In a specific embodiment of the present invention, the laser-transparent polymer composition comprises the following: -40-94.8 wt.% of component (A); -0.2-5 wt.% of component (B); -5-50 wt.% of the component (C); -0-5 wt.% of component (D); and -0-20 wt.% of the component (E); Wherein, the weight percentage (wt.%) is relative to the total weight of the composition.

[0086] In another embodiment of the invention, the laser-transparent polymer composition comprises the following: -40-99.79 wt.% of component (A); -0.2-5 wt.% of component (B); -0-50 wt.% of the component (C); -0.01-5 wt.% of component (D); and -0-20 wt.% of the component (E); Wherein, the weight percentage (wt.%) is relative to the total weight of the composition.

[0087] An embodiment of the composition according to the invention comprises a composition of 99 pbw component (A), 1.0 pbw component (B), and 98 pbw component (C). Component (C) is present in an amount of 49.5 wt.% relative to the total weight of the composition.

[0088] Another embodiment of the composition according to the invention is a composition consisting of 98 pbw of component (A), 2.0 pbw of component (B), and 15 pbw of component (C). Hereinafter, component (C) is present in an amount of 13.0 wt.% relative to the total weight of the composition. When the composition comprises 98 pbw of component (A), 2.0 pbw of component (B), and 15 pbw of component (C), and one or more additional components (component (E)), the weight percentage of component (C) relative to the total weight of the composition may be less than 13.0 wt.%, for example, 10 wt.%.

[0089] Another embodiment of the composition according to the invention is a composition consisting of 99 pbw of component (A), 1.0 pbw of component (B), and 2.5 pbw of component (D). Herein, component (D) is present in an amount of 2.43 wt.% relative to the total weight of the composition. Another embodiment of the composition according to the invention is a composition consisting of 98 pbw of component (A), 2.0 pbw of component (B), and 1.1 pbw of component (D). Herein, component (D) is present in an amount of 1.06 wt.% relative to the total weight of the composition. When the composition comprises 98 pbw of component (A), 2.0 pbw of component (B), and 1.1 pbw of component (D), and one or more additional components (component (E)), the weight percentage of component (D) relative to the total weight of the composition may be less than 1.06 wt.%, for example, 0.96 wt.%.

[0090] Another embodiment of the composition according to the invention comprises a composition of 99 pbw component (A), 1.0 pbw component (B), 98 pbw component (C), and 2.5 pbw component (D). Herein, component (C) is present in an amount of 48.9 wt.% relative to the total weight of the composition, while component (D) is present in an amount of 1.25 wt.% relative to the total weight of the composition. Another embodiment of the composition according to the invention comprises a composition of 98 pbw component (A), 2.0 pbw component (B), 15 pbw component (C), and 1.1 pbw component (D). Herein, component (C) is present in an amount of 12.9 wt.% relative to the total weight of the composition, while component (D) is present in an amount of 0.95 wt.% relative to the total weight of the composition. In the case where the composition contains one or more additional components (component (E)) in addition to component (A) of 98 pbw, component (B) of 2.0 pbw, component (C) of 15 pbw, and component (D) of 1.1 pbw, the weight percentages of components (C) and (D) relative to the total weight of the composition may be less than 12.9 wt.% and 0.95 wt.%, respectively, for example less than 11.5 wt.% and 0.85 wt.%, respectively.

[0091] The laser-transparent compositions according to various embodiments of the invention have a laser transparency of at least 25.0% (experimental portion) measured at 1 mm thickness and 980 nm by the method according to TMG3, as further described below. Preferably, the laser transparency measured at 1 mm thickness and 980 nm is at least 30.0%, more specifically at least 35.0%, and even more specifically at least 40.0%.

[0092] Method for preparing laser-transparent polymer compositions

[0093] The present invention also relates to methods for preparing laser-transparent polymer compositions that can be used in various embodiments of the invention. The compositions described herein, and any specific or preferred embodiments thereof, can be produced by methods known per se: by melting component (A), and mixing components (A) and (B), and optionally also components (C) and / or component (D), or additional components in amounts as indicated above for the compositions of the invention or for different embodiments thereof.

[0094] In this document, the method or compounding method for preparing laser-transparent polymer compositions includes the step of melt mixing components comprising: (A) PBT resin; and (B) dialkali metal salts of norbornane-2,3-dicarboxylic acid, and / or their substituted derivatives; and at least one component selected from (C) and (D), wherein (C) is glass fiber and (D) is colorant.

[0095] Suitablely, the mixing method includes melting and mixing the components in the following amounts: (A) at least 35 wt.% of component (A); and (B) 0.2-5.0 wt.% of component (B); as well as At least one component selected from (C) and (D), wherein (C) is glass fiber in an amount of 5 wt% to 50 wt%; and (D) is a colorant in an amount of 0.01 to 2.5 wt%. (e) 0-20 wt.% of one or more other components; - Wherein, the weight percentage (wt.%) is relative to the total weight of the composition, and -The amount of component (B) is in the range of 0.2-6.0 parts by weight (pbw), relative to the combined amount of components (A) and (B) of 100 pbw.

[0096] Furthermore, in this paper, the combined amount of components (A)-(E) is equal to 100 wt.%.

[0097] In a preferred embodiment, the colorant used in the composite method comprises, or even consists of, a laser-transparent colorant; more specifically, a laser-transparent colorant as described above.

[0098] The mixing method according to the invention is a melt mixing method, comprising melting (A) PBT resin and mixing it with (B) a dialkali metal salt of norbornane-2,3-dicarboxylic acid and / or its substituted derivatives; and optionally (C) one or more of glass fibers; (D) a colorant; and / or (E) one or more additional components. Herein, the components are suitably selected from the above-described components and their amounts and preferred embodiments.

[0099] Melt mixing can be carried out in conventional mixing equipment such as single-screw and twin-screw extruders, Brabender mixers, or Banbury mixers, and then the melt mixture of components is extruded to produce an extrudate. The extrudate can be cooled and optionally granulated, pelletized, ground, or otherwise reduced to granules or fragments. The mixing temperature is suitably 230–320°C.

[0100] These components can be added simultaneously or separately. Suitably, component (A) can be melted first and then mixed with other components, or the melting of component (A) and mixing with one or more other components can be carried out simultaneously, or component (A) can be mixed with one or more other components first and then melted. For example, components (A) and (B), and where applicable, components (D) and / or (E) can be added to the first extruder inlet and mixed and heated, and component (C) can be added to the second extruder inlet and combined with the mixed components (A) and (B), and optionally (C) and / or (D). Component (A) can also be added to the first extruder inlet and heated, while components (B) and / or optionally (C) and / or (D) can be added to the second extruder inlet and combined with component (A). Component (B) can also be added in a premixed form; for example, in the form of a masterbatch. Such a masterbatch suitably comprises a portion of the PBT resin of components (B) and (A), while the remaining portion of the PBT resin of component (A) is added and processed in the melt-mixing process described above.

[0101] Method for preparing laser-transparent molded parts

[0102] The present invention also relates to a method for preparing molded articles from a laser-transparent polymer composition. The method includes molding a laser-transparent polymer composition into a pre-formed shape, the laser-transparent polymer composition being any of the specific or preferred embodiments of the invention as described herein.

[0103] In this article, the laser-transparent polymer composition comprises at least: (A) PBT resin; and (B) dialkali metal salts of norbornane-2,3-dicarboxylic acid, and / or their substituted derivatives; and / or - Polyester copolymers (referred to as A / B copolymers) comprise repeating units derived from dialkane-2,3-dicarboxylic acid and / or their substituted derivatives, which are incorporated into the PBT resin.

[0104] Suitablely, the laser-transparent composition comprises the following: (A / B) at least 35.2 wt.% of components (A) and (B), and / or, if present, the A / B copolymer; (C) 0-50 wt.% glass fiber; (D) 0-2.5 wt.% colorant; and (E) 0-20 wt.% of one or more other components; - Wherein, the weight percentage (wt.%) is relative to the total weight of the composition, and -The amount of component (B) is in the range of 0.2-6.0 parts by weight (pbw), relative to 100 pbw of components (A) and (B), and the combined amount of the A / B copolymer if present.

[0105] The composition preferably comprises at least one component selected from (C) and (D), wherein (C) is 5-50 wt% of glass fiber; and (D) is 0.01-2.5 wt% of colorant, wherein the weight percentage (wt.%) is relative to the total weight of the composition.

[0106] The laser-transparent polymer composition of the present invention can be molded by methods known per se: the molded parts can be made, for example, by injection molding, molding, compression molding, or pultrusion. The molded parts are preferably made by injection molding. For this method, conventional equipment and conventional process conditions can be used.

[0107] In a preferred embodiment of the molded part and the molding method for preparing the molded part, the colorant contained in the laser-transparent polymer composition used therein comprises a laser-transparent colorant, or even consists of a laser-transparent colorant; more specifically, a laser-transparent colorant as described above.

[0108] Laser transparent molding parts

[0109] The present invention also relates to laser-transparent molded parts made from laser-transparent polymer compositions. In this document, the laser-transparent polymer composition is the composition according to the invention as described above, or a composition of any of its various embodiments.

[0110] The advantages of these molded parts are not only that they are suitable for laser welding processes via laser transmission welding, but also that they exhibit a better overall balance in terms of laser transparency and tensile elongation at break, as well as retention of the relative solution viscosity (RSV) of the PBT resin therein. These advantages are further enhanced for compositions in which component (B) is present in an amount ranging from 0.2 to 6.0 parts by weight (pbw), preferably 0.3 to 5.0 pbw, more preferably 0.4 to 4.0 pbw, relative to 100 pbw of the combined amount of components (A) and (B).

[0111] The laser transparency of these molded parts is preferably at least 25.0%, more specifically at least 30.0%, and even more specifically at least 40%, measured at a thickness of 1.0 mm and 980 nm using the method of TMG3, which is further described herein (experimental section). The molded parts also preferably have a transparency of at least 15.0%, more specifically at least 17.5%, and even more specifically at least 20.0%, measured at a thickness of 2.0 mm and 980 nm using the method of TMG3, which is further described herein.

[0112] Use of the composition or molded parts made therefrom

[0113] The laser-transparent polymer compositions of the present invention and their various specific and preferred embodiments, as well as the molded parts made from these laser-transparent polymer compositions, are suitable for the production of laser-welded products.

[0114] Method for preparing laser-welded objects

[0115] The present invention also relates to a method for producing laser-welded objects by laser transmission welding, and laser-welded objects obtainable by laser transmission welding. The method includes providing a first molded part (P1) comprising a laser-transparent polymer composition (I) and a second molded part (P2) comprising a laser-absorbing polymer composition (II), and arranging P1 and P2 to form a contact surface between P1 and P2. The method further includes irradiating the contact surface with a laser beam, thereby producing a laser-welded object in which P1 and P2 are joined by laser welding.

[0116] The process of laser welding (also known as laser transmission welding) and the equipment used therein are known in the art. The basic principles of laser welding are described in technical literature, such as Plastverarbeiter 46 (1995) 9, 42-46, Kunststoffe 87, (1997) 3, 348-350; Kunststoffe 87 (1997) 11, 1632-1640; Kunststoffe 88, (1998), 2, 210-212; and Plastverarbeiter 50 (1999) 4, 18-19. For example, European Patent EP1048439B1 describes an embodiment of this method and the apparatus used therein.

[0117] The method according to the present invention includes at least the following steps: a. Provide a first molded part (P1) comprising a laser-transparent polymer composition (I); b. Provide a second molding (P2) comprising a laser-absorbing polymer composition (II); c. Combine the first part (P1) and the second part (P2); and d. Perform laser transmission welding on the combined components to bond the first molded part (P1) to the second molded part (P2); The first molded part (P1) comprises a laser-transparent polymer composition (I), which includes: (A) PBT resin; and (B) dialkali metal salts of norbornane-2,3-dicarboxylic acid, and / or their substituted derivatives; and / or - A polyester copolymer comprising repeating units of an alkali metal salt derived from norbornane-2,3-dicarboxylic acid and / or its substituted derivatives incorporated into a PBT resin (A) (the polyester copolymer is referred to as an A / B copolymer).

[0118] In the laser transmission welding method according to the invention, the laser-transparent polymer composition (I) can be any composition comprising PBT resin (component (A)); a dialkali metal salt of norbornane-2,3-dicarboxylic acid, and / or its substituted derivatives (component (B)); and / or an A / B copolymer; and optionally any other one or more components, provided that the composition has sufficient laser transparency. The PBT resin (component (A)) can be any PBT resin suitable for use in molding the composition, and is preferably the PBT resin mentioned herein. Component (B) is suitably a dialkali metal salt of norbornane-2,3-dicarboxylic acid and / or its substituted derivatives, or a preferred embodiment thereof, as described above. One or more additional components are suitably selected from components (C), (D), and (E) mentioned above. Suitably, the laser-transparent polymer composition (I) is a composition according to the invention, or any specific embodiment thereof as described above.

[0119] In the laser transmission welding method according to the invention, a first molded part (P1) is bonded to a second molded part (P2) comprising a laser-absorbing polymer composition (II). Hereinafter, (P1) functions as a laser-transparent polymer portion and (P2) as a laser-absorbing polymer substrate. The laser-absorbing polymer substrate can be any molded part made of any laser-absorbing polymer material. For example, these can be thermoplastic materials, thermosetting materials, or composite materials. Preferably, the laser-absorbing polymer substrate is made of a thermoplastic composition comprising a thermoplastic polymer and having sufficient laser absorption in the wavelength range used. The thermoplastic polymer in the laser-absorbing polymer substrate is preferably a thermoplastic polymer miscible with the polyester in the laser-transparent polymer composition (I). More preferably, the thermoplastic composition comprises a thermoplastic polyester. The thermoplastic polyester can be, for example, PBT, or PET, or PCT, or any mixture or copolymer thereof. Most preferably, the thermoplastic composition in the laser-absorbing polymer substrate comprises PBT.

[0120] Thermoplastic compositions can be suitably made laser-absorbing by adding inorganic pigments, organic pigments, fillers, or other additives, or any combination thereof. Suitable additives are known in the art. Examples include carbon fibers, carbon black, graphite, graphene, and carbon nanotubes. Carbon black and graphite are highly effective for laser absorption. Carbon black or graphite, or combinations thereof, are preferably used as laser-absorbing substrates.

[0121] For the laser welding process according to the present invention, the advantages mentioned above for molded parts, including a better overall balance in laser transparency and mechanical properties, as well as shorter laser welding cycle time or higher welding strength, also apply here.

[0122] Laser welding objects

[0123] The present invention also relates to laser-welded objects comprising two molded parts (P1) and (P2) welded together by laser transmission welding.

[0124] In the laser-welded object according to the invention, a first molded part (P1) comprises a laser-transparent polymer composition (I) and a second molded part (P2) comprises a laser-absorbing polymer composition (II); wherein the laser-transparent polymer composition (I) is the composition described above, and preferably is the laser-transparent polymer composition according to the invention, or any different embodiment thereof as described above. The advantage of this laser-welded object is that the laser-transparent polymer composition has a better overall balance in laser transparency and mechanical properties, as described above.

[0125] In a preferred embodiment of the invention, the laser-absorbing polymer composition (II) in the laser-welded object and included in the molding part (P2) in the laser welding method for preparing the laser-welded object is made of a thermoplastic composition comprising polybutylene terephthalate (PBT) resin and carbon black and / or graphite.

[0126] The laser-welded objects according to the present invention and obtainable by the method according to the present invention are suitable for use in electrical applications, electronic products, telecommunications products, information technology, computers, home, sports, medical, motor vehicles, or entertainment products.

[0127] The present invention further includes electrical components, electronic devices, household articles, sporting goods, medical devices, motor vehicles, or products in the entertainment field that include laser-welded objects according to the present invention.

[0128] The present invention is further illustrated by the following embodiments and comparative experiments.

[0129] Experimental Section

[0130] Material

[0131] (A-1) Polyester: Polybutylene terephthalate, having a melt temperature of 224±2°C (measured by means of ISO 11357 at a heating ramp of 20°C / min), a relative solution viscosity (RSV) of 2.36±0.04 dl / g (measured by means of ISO 307 at 25°C in 100g of m-cresol at a concentration of 1g), and a melt volumetric rate (MVR) of 11.5±1.0 cm3 / 10min (measured by means of ISO 1133 at 250°C, 2.16kg).

[0132] (B-1) Disodium salt of norbornane-2,3-dicarboxylic acid.

[0133] (Ba) Sodium lignite (sodium salt of lignite acid).

[0134] (Bb) Sodium carbonate.

[0135] (Bc) Disodium oxalate.

[0136] (Bd) Disodium succinate.

[0137] (C-1) Glass fiber: E-glass, standard grade chopped fiber for thermoplastic polyester injection molding compounds.

[0138] (D-1) Black coloring combination of non-black laser transparent colorant: eBind LTW-8904 (commercially available from OCI).

[0139] deal with

[0140] Mixed

[0141] These molding compositions were produced in a ZSK25 twin-screw extruder, which has a flat temperature characteristic profile from 290°C to 320°C and also has a granulation function. Components (A-1) and (Bx) were premixed and fed at the throat, while component (C-1) was fed at the side feeder.

[0142] Molding

[0143] Prior to molding, the material was dried at 120°C for 16 hours in a vacuum oven with N2 purification. To prepare test samples, injection molding was performed on a Fanuc-2 type injection molding machine (α-S50iA type) with a suitable mold cavity and a barrel temperature of 260°C and a mold cavity temperature of 90°C.

[0144] - For laser transparency testing, prepare test samples of 80 x 80 mm and 1.0 mm thickness.

[0145] - For tensile testing, prepare test specimens according to ISO 527-1A.

[0146] Test methods

[0147] Laser transparency measurement

[0148] Using a TMG3 measurement unit equipped with a laser source, the laser transparency is measured at the midpoint of an injection-molded test sample (80x80 mm plate) with a thickness of 1 mm, by applying the steps described in TMG3 User Manual Version 3.0, Serial No. 1500209 (referred to herein as the method according to TMG3). The laser source illuminates the sample at a wavelength of 980 nm. The TMG3 measurement unit is available from LPKF WeldingQuipment GmbH, Alfred-Nobel-Straße 55-57, 90765 Fürth, Germany.

[0149] As described above, injection molding is performed using standard PBT molding conditions.

[0150] Mechanical properties

[0151] The tensile elongation at break was measured in accordance with ISO 527-1A (2019) in a tensile test on a 4 mm thick test specimen at 23°C and a tensile rate of 5 mm / min.

[0152] Viscosity

[0153] The relative solution viscosity of the polymer was measured at a concentration of 1 g in 100 g of m-cresol at 25°C according to the method of ISO 307.

[0154] 1 H-NMR

[0155] For the application of norbornene dicarboxylic acid disodium salt in PBT homopolymers, examples are given for determining the amount of component (B) in the composition according to the invention or used. 1 H-NMR method.

[0156] Approximately 15 mg of sample was weighed into a 5 mm NMR tube, and 0.7 mL of a mixture of CDCl3 / TFA-d 90 / 10 was added. TFA is trifluoroacetic acid. The tube was then heated to 40°C for 6 hours under constant rotation until the polymer fraction appeared to be completely dissolved. Recordings were then performed at 40°C on a Bruker AvanceIII HD 500 MHz spectrometer equipped with a 5 mm broadband cryopreservation probe. 11H NMR spectra. A total of 32 scans were recorded using 90-degree pulses and a 60-second relaxation delay. For processing, a 0.3 Hz line broadening was applied. Baseline correction was performed manually using a fifth-order polynomial function across the region of interest (between 9.5 ppm and -0.5 ppm). The peak at 8.2 ppm originates from terephthalic acid (TPA) in the PBT resin and corresponds to 4 hydrogens per repeating unit. The peaks at approximately 3.5 and 2.9 ppm originate from norbornane dicarboxylic acid as a carboxylic acid ester and each corresponds to 2H. The peaks at 3.2 and 2.7 ppm originate from norbornane dicarboxylic acid esters and also each correspond to 2H.

[0157] In this composition, norbornane dicarboxylic acid (NDCA) can exist as a carboxylate (NDCA-carboxylate), or esterified, i.e., as an ester (NDCA ester), or both. The norbornane dicarboxylic acid content and degree of esterification are calculated as follows. Peak integration is performed manually. Let I A I is the integral of the terephthalic acid signal; B It is the integral sum of the NDCA-carboxylic acid ester signals at 3.5 and 2.9 ppm, I C The ester is the sum of the integrals from the two peaks of NDCA. The degree of esterification (ester%) is calculated as follows: Then, N ester% = I C / (I B +I C ) 100% The weight percentage of NDCA (NDCA%) is calculated as follows: NDCA%=(I B +I C ) M NDCA / {I A M 0, PBT +(I B +I C ) M NDCA} 100% Here, M NDCA It is the molar mass of disodium norbornene dicarboxylate, 230 g / mol, and M 0, PBT It is the molar mass of the repeating unit in the PBT homopolymer, 220 g / mol.

[0158] The above examples illustrate the use of disodium norbornene dicarboxylate in PBT homopolymers. 1 The H-NMR method can be applied in the same way to other alkali metal salts of norbornane dicarboxylic acid and its substituted derivatives, thus employing appropriate molecular weights and appropriate numbers of hydrogen atoms.1 The H-NMR method can be applied to PBT copolymers in the same way, by correcting the weight percentage of NDCA (NDCA%) by applying an appropriate molar mass of repeating terephthalic acid units and their weight percentage in the PBT copolymer.

[0159] Composition and test results

[0160] Tables 1-3 report the compositions (embodiments) and comparative compositions (comparative experiments) according to the present invention, as well as the test results obtained using these embodiments and comparative experiments.

[0161] Table 1: Composition and results at 0.5 wt.% additive BX (Reference: 0 wt.%; 0.75 wt.% sodium lignite) (Ba))

[0162] Table 2: Composition and results at 1.0 wt.% additive BX (reference: 0 wt.%)

[0163] Table 3: Composition and results with 2.0 wt.% additive BX (Reference: 0 wt.%; 1.75 wt.% lignite acid) sodium)

[0164] The results in Tables 1-3 illustrate that the compositions according to the invention (Example I, Table 1; Example II; Table 2, Example III, Table 3), comprising disodium salt of norbornene-2,3-dicarboxylic acid in amounts of 0.5 wt.%, 1.0 wt.%, and 2.0 wt.%, respectively, combined with PBT resin, and the other three comprising glass fibers, with Example I and Example III also comprising a black coloring composition containing a non-black laser-clearing colorant (D-1), show a significant improvement in laser transparency and very good retention in elongation at break and relative solution viscosity (RSV) compared to the corresponding comparative compositions not containing disodium salt (Comparative Experiment CE-A in Tables 1 and 3, and CE-B in Table 2).

[0165] Compared with other comparative experiments, including disodium salts of norbornene-2,3-dicarboxylic acid and sodium salts of other carboxylic acids (including disodium salts of other dicarboxylic acids), the compositions of Examples I-III exhibited the highest percentage of elongation at break and the highest RSV values. This is combined with the already mentioned high laser transparency.

[0166] The composition used in the comparative experiment with disodium oxalate (component (Bc)) and disodium succinate (component (Bd)) showed slightly lower retention in RSV, but no improvement in laser transparency. This made things worse.

[0167] The compositions used in comparative experiments with sodium lignite (component (Ba)) and disodium carbonate (component (Bb)) showed higher values ​​for laser transparency, but lower percentages of elongation at break and lower retention in RSV. This became worse at higher concentrations of 1 wt.%, and even worse at 2.0 wt.% and above. For Example III, the compositions according to the invention, having 2 wt.% of the disodium salt of norbornane-2,3-dicarboxylic acid, still showed relatively good retention in RSV, and even the highest elongation at break.

Claims

1. A laser-transparent polymer composition comprising... (A) Polybutylene terephthalate resin (PBT resin; component (A)); and (B) dialkali metal salts of norbornane-2,3-dicarboxylic acid, and / or their substituted derivatives (component (B)). and / or - A polyester copolymer comprising repeating units incorporated into a PBT resin, the repeating units being derived from a dialkali metal salt of norbornane-2,3-dicarboxylic acid and / or its substituted derivatives (the polyester copolymer is referred to as an A / B copolymer). And at least one component selected from (C) and (D), wherein (C) is glass fiber and (D) is a colorant.

2. The laser-transparent polymer composition according to claim 1, wherein the PBT resin (component (A)) is: -PBT homopolymer; or -PBT copolymer, relative to the total molar amount of butene units, terephthalate units and comonomer units in the copolymer, comprises at least 90 mol% of butene and terephthalate comonomer units and at most 10.0 mol% of comonomer comonomer units.

3. The laser-transparent polymer composition according to claim 1 or 2, wherein components (A) and (B), and if present, the A / B copolymer, are present in a combined amount of at least 35.2 wt.% relative to the total weight of the laser-transparent polymer composition.

4. The laser-transparent polymer composition according to any one of claims 1-3, wherein, relative to 100 pbw of components (A) and (B) and, if present, the combined amount of the A / B copolymer, component (B) is in the range of 0.2-6.0 parts by weight (pbw) in itself and / or incorporated in the A / B copolymer.

5. The laser-transparent polymer composition according to any one of claims 1-4, wherein the dialkali metal salt of norbornane-2,3-dicarboxylic acid and / or its substituted derivatives (component (B)) comprises disodium norbornane-2,3-dicarboxylic acid.

6. The laser-transparent polymer composition according to any one of claims 1-5, wherein the composition comprises (C) 5-50 wt.% glass fiber; and / or (D) 0.01-2.5 wt.% of the colorant; and optional (E) 0-20 wt.% of one or more other components; in, Weight percentage (wt.%) is relative to the total weight of the composition.

7. The laser-transparent polymer composition according to any one of claims 1-6, wherein the laser-transparent polymer composition has at least 25% laser transparency at a thickness of 1 mm and measured by the method according to TMG3 as described above.

8. A laser-welded object comprising two molded parts (P1) and (P2) welded together by laser transmission welding, wherein... - The first molded part (P1) comprises a laser-transparent polymer composition (I); and - The second molding part (P2) contains a laser-absorbing polymer composition (II); in, The laser-transparent polymer composition (I) comprises: (A) Polybutylene terephthalate resin (PBT resin); and (B) dialkali metal salts of norbornane-2,3-dicarboxylic acid, and / or their substituted derivatives; and / or - Polyester copolymers (referred to as A / B copolymers) include repeating units incorporated into PBT resins, said repeating units being derived from dialkali metal salts of norbornane-2,3-dicarboxylic acid and / or their substituted derivatives.

9. The laser-welded object according to claim 8, wherein the laser-transparent polymer composition (I) comprises the following: (A / B) at least 35.2 wt.% of components (A) and (B), and / or, if present, their A / B copolymers; and (C) 0-50 wt.% glass fiber; and / or (D) 0-2.5 wt.% colorant; and / or (E) 0-20 wt.% of one or more other components; - Wherein, the weight percentage (wt.%) is relative to the total weight of the laser-transparent polymer composition; and - wherein, relative to 100 pbw of components (A) and (B), and if present, the amount of component (B) in combination with the A / B copolymer, is in the range of 0.2-6.0 parts by weight (pbw).

10. The laser-welded object according to claim 8 or 9, wherein the laser-transparent polymer composition (I) is the laser-transparent polymer composition according to any one of claims 1-7.

11. A method for preparing a laser-welded object, comprising at least the following steps: a. Provide a first part (P1) comprising a laser-transparent polymer composition (I); b. Provide a second part (P2) comprising the laser-absorbing polymer composition (II); c. Combine the first part (P1) and the second part (P2); and d. The assembled components are subjected to laser transmission welding to bond the first part (P1) to the second part (P2); The first portion (P1) comprises a laser-transparent polymer composition (I), which includes: (A) Polybutylene terephthalate resin (PBT resin); and (B) dialkali metal salts of norbornane-2,3-dicarboxylic acid, and / or their substituted derivatives; and / or - A polyester copolymer comprising repeating units incorporated into a PBT resin, the repeating units being derived from a dialkali metal salt of norbornene-2,3-dicarboxylic acid and / or its substituted derivatives (the polyester copolymer is referred to as an A / B copolymer).

12. Use of a laser-welded object according to any one of claims 8-10 or a laser-welded object obtainable by the method according to claim 11 in applications selected from: electrical applications, electronic products, telecommunications products, information technology, computers, home, sports, medical, motor vehicles, or entertainment fields.

13. A method for preparing a laser-transparent polymer composition, the method comprising the step of melt-mixing components comprising: (A) Polybutylene terephthalate resin (PBT resin); and (B) dialkali metal salts of norbornane-2,3-dicarboxylic acid, and / or their substituted derivatives; and at least one component selected from (C) and (D), wherein (C) is glass fiber and (D) is a colorant.

14. The method of claim 13, comprising melt-mixing the following: (A) at least 35 wt.% of component (A); and (B) 0.2-5.0 wt.% of component (B); and at least one component selected from (C) and (D), wherein (C) is 5-50 wt% glass fiber; and (D) is 0.01-2.5 wt% colorant; and optional (E) 0-20 wt.% of one or more other components; -in, Weight percentage (wt.%) is relative to the total weight of the composition, and -The amount of component (B) is in the range of 0.2-6.0 parts by weight (pbw) relative to the combined amount of components (A) and (B) of 100 pbw.

15. A method for preparing a laser-transparent molded part, the method comprising the following steps: i. Providing a laser-transparent polymer composition comprising (A) Polybutylene terephthalate resin (PBT resin); and (B) dialkali metal salts of norbornane-2,3-dicarboxylic acid, and / or their substituted derivatives; and / or - Polyester copolymers (referred to as A / B copolymers) include repeating units incorporated into PBT resins, said repeating units being derived from dialkali metal salts of norbornane-2,3-dicarboxylic acid and / or their substituted derivatives; ii. The laser-transparent polymer composition is molded by injection molding, compression molding, or pultrusion to form the molded part; injection molding is preferred.

16. The method of claim 15, wherein the laser-transparent polymer composition comprises: (A / B) at least 35.2 wt.% of components (A) and (B), and / or, if present, the A / B copolymer; (C) 0-50 wt.% glass fiber; (D) 0-2.5 wt.% laser-transparent colorant; as well as (E) 0-20 wt.% of one or more other components; - Wherein, weight percentage (wt.%) is relative to the total weight of the composition, and - wherein, relative to 100 pbw of components (A) and (B), and if present, the amount of component (B) is in the range of 0.2-6.0 parts by weight (pbw).

17. A laser-transparent molded part made of a laser-transparent polymer composition, obtainable by the method according to claim 15 or 16, wherein the laser-transparent polymer composition has at least 25% laser transparency at a thickness of 1 mm and at a wavelength of 980 nm as measured by the method according to TMG3 as described above.

18. Use of a composition or a molded part made therefrom for laser transmission welding, said composition comprising at least 35.2 wt.% of the following items in a combined amount relative to the total weight of said composition: (A) Polybutylene terephthalate resin (PBT resin); and (B) a dialkali metal salt of norbornane-2,3-dicarboxylic acid, or a substituted derivative thereof; and / or - Polyester copolymers (referred to as A / B copolymers) contain repeating units incorporated into PBT resin, said repeating units being derived from dialkali metal salts or their substituted derivatives; -in, The amount of component (B) in the A / B copolymer, either as is or incorporated therein, is in the range of 0.2-6 parts by weight (pbw) relative to 100 pbw of components (A) and (B) and, if present, the combined amount of the A / B copolymer.

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