Insert coating via injection molding

Abstract

An in-mold package and method for manufacturing the same are disclosed, comprising two or more plastic molded parts and a coating such that when the package is rotated 360 degrees about an axis, a portion of the coating applied to the outer surface of the molded parts is visible at any angle about the axis. In one embodiment, the molded parts comprise polycarbonate, and the coating composition comprises isocyanate-reactive groups and a polyisocyanate. The package may include areas where no coating is applied, even if the coating alone, and not any other adhesive or structure, holds the plastic molded parts together.

Description

Technical Field

[0001] The present disclosure relates to methods for in-mold encapsulation of multiple molded parts and products formed therefrom. Background Art

[0002] Two-component compositions that form polyurethanes are widely used due to the many advantageous properties they exhibit. These curable compositions typically comprise a liquid binder component and a liquid hardener / crosslinker component. The liquid binder component may include an isocyanate-reactive component, such as a polyol, and the liquid crosslinker component may include a polyisocyanate. The addition reaction of the polyisocyanate with the isocyanate-reactive component, which can occur under ambient conditions, produces a crosslinked polyurethane network that forms a coating film. Polyurethane coatings are used in a variety of applications, one of which is commonly referred to as "in-mold" coating.

[0003] In in-mold coating applications, a coating film is molded onto the surface of a substrate. In in-mold coating methods utilizing multi-cavity metal molds, a molded plastic part is formed in one cavity of the mold and introduced into a second cavity of the mold, where the coating film is injected. However, such methods do not enclose or encapsulate the molded plastic part.

[0004] Coatings designed to surround or encapsulate plastic parts are applied by immersing the part in a liquid that subsequently solidifies as a solid coating on the part. However, this method requires significantly more coating material than can actually be applied to the part. Furthermore, this method can only be used with certain coatings that remain liquid but solidify when removed from the immersion tank.

[0005] Overview

[0006] Disclosed herein is a method for in-mold coating, comprising introducing a first plastic molded part into a cavity of a mold; introducing a second plastic molded part into the cavity, wherein the first molded part and the second molded part fit together to form an assembly having an outer surface; introducing a coating composition into the cavity; and curing the coating on the outer surface of the assembly, wherein the coating flows in a gap between the outer surface of the assembly and the cavity, and wherein the coating flows 360 degrees around the outer surface of the assembly such that when the coated assembly is rotated 360 degrees about an axis, the coating can be seen applied to a portion of the outer surface of the assembly at any angle about the axis.

[0007] Also disclosed herein is a package comprising: a first plastic molded part; a second plastic molded part, wherein the first molded part and the second molded part cooperate together to form an assembly having an outer surface; a cured coating located on the outer surface of the assembly, wherein the coating flows 360 degrees around the outer surface of the assembly so that when the coated assembly is rotated 360 degrees about an axis, the coating can be seen applied to a portion of the outer surface of the assembly at any angle about the axis, and wherein the package does not include any other adhesive or structure.

[0008] In one embodiment, the first plastic molded part comprises polycarbonate.In another embodiment, the second plastic molded part comprises polycarbonate.

[0009] In another embodiment, the coating composition comprises (i) a first polymer component comprising a polymer containing one or more isocyanate-reactive groups and (ii) a second polymer component comprising a polyisocyanate. Optionally, the first polymer component is a polyether polyol or a polycarbonate polyol. Furthermore, the second polymer component may be a diisocyanate. In another embodiment, the second polymer component comprises a polyisocyanurate. In yet another embodiment, the second polymer component comprises biuret groups.

[0010] In another embodiment not yet disclosed, the coating composition further comprises an internal mold release agent. In various embodiments, the first plastic molded part and the second plastic molded part comprise one or more indentations. In another embodiment, the outer surface of the assembly comprises one or more portions that are uncoated and one or more other portions that are coated.

[0011] In various embodiments, the first plastic molded part and the second plastic molded part are held together only by the cured coating and not by any other adhesive or structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The subject matter which is regarded as the embodiment is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features and advantages of the embodiments are apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0014] Figure 1 is a front view of the first molded part;

[0015] Figure 2 yes Figure 1 a rear view of the first molded part;

[0016] Figure 3 is a front view of the second molded part;

[0017] Figure 4 yes Figure 3 a rear view of the second molded part;

[0018] Figure 5 is a front view of the package of two molded parts;

[0019] Figure 6 yes Figure 5 a rear view of the package;

[0020] Figure 7 is a perspective view of a tool for forming an enclosure of two molded parts;

[0021] Figure 8 yes Figure 7 A perspective view of the tool shown in with the cover removed; and

[0022] Figure 9 It is from Figure 8 The opposite direction shows Figure 7 Another perspective view of the tool with the cover removed.

[0023] Detailed description

[0024] Various examples are described and illustrated herein to provide a comprehensive understanding of the structure, function, operation, manufacture, and use of the disclosed products and methods. The various examples described and illustrated herein are non-limiting and non-exhaustive. Therefore, the present invention is not limited by the description of the various non-limiting and non-exhaustive examples disclosed herein. Rather, the present invention is limited only by the claims. The features and characteristics shown and / or described in conjunction with the various examples may be combined with the features and characteristics of other examples. Such modifications and variations are intended to be included within the scope of this specification. Therefore, the claims may be amended to recite any feature or characteristic explicitly or inherently described in this specification or otherwise explicitly or inherently supported by this specification. Further, applicants reserve the right to amend the claims to affirmatively disclaim claims for features or characteristics that may exist in the prior art. Therefore, any such modifications comply with the requirements of 35 USC § 112 and 35 USC § 132(a). The various embodiments disclosed and described in this specification may include, consist of, or consist essentially of the features and characteristics described from various perspectives herein.

[0025] Unless otherwise indicated, any patent, publication, or other public material identified herein is incorporated herein by reference in its entirety, but only to the extent that the incorporated material does not conflict with existing definitions, statements, or other public materials explicitly set forth in this specification. Therefore, to the extent necessary, the explicit disclosure set forth in this specification supersedes any conflicting material incorporated herein by reference. Any material or portion thereof (which is considered incorporated by reference into this specification, but which conflicts with existing definitions, statements, or other public materials set forth herein) is incorporated only to the extent that no conflict arises between the incorporated material and the existing public materials. Applicants reserve the right to amend this specification to explicitly recite any subject matter, or portion thereof, incorporated herein by reference.

[0026] References throughout the specification to "various aspects," "some aspects," "an aspect," or "aspects," similar language associated with "an example," and the like mean that a particular feature, structure, or characteristic described in connection with the example is included in at least one aspect. Thus, the appearance of the phrases "in various aspects," "in some aspects," "in an aspect," or "in an aspect," similar language associated with "an example," and the like somewhere throughout the specification do not necessarily refer to the same aspect. Furthermore, particular features, structures, or characteristics may be combined in any suitable manner in one or more aspects. Thus, particular features, structures, or characteristics shown or described in connection with one example or aspect may be combined, in whole or in part, with features, structures, or characteristics of one or more other examples or aspects, without limitation. Such modifications and variations are intended to be included within the scope of the present aspects.

[0027] In this specification, unless otherwise indicated, all numerical parameters are to be understood as being preceded and modified in all instances by the term "about," wherein numerical parameters are characterized by the inherent variability of the underlying measurement technology employed to determine the parameter's value. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter described herein should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0028] As used herein, "polymer" includes prepolymers, oligomers, and homopolymers and copolymers; in this case, the prefix "poly" refers to two or more. As used herein, "molecular weight" when used in reference to a polymer refers to the number-average molecular weight ("M"). n ”), unless otherwise indicated. As used herein, polymers containing functional groups such as polyols n It can be calculated from the number of functional groups, such as the hydroxyl number, which is determined by end group analysis, as is well known to those skilled in the art.

[0029] As used herein, the term "aliphatic" refers to organic compounds characterized by a substituted or unsubstituted linear, branched, and / or cyclic chain arrangement of the constituent carbon atoms. Aliphatic compounds do not contain aromatic rings as part of their molecular structure. As used herein, the term "cycloaliphatic" refers to organic compounds characterized by an arrangement of carbon atoms in a closed ring structure. Cycloaliphatic compounds do not contain aromatic rings as part of their molecular structure. Therefore, cycloaliphatic compounds are a subset of aliphatic compounds. Therefore, the term "aliphatic" includes aliphatic compounds and / or cycloaliphatic compounds.

[0030] As used herein, "diisocyanate" refers to a compound containing two isocyanate groups. As used herein, "polyisocyanate" refers to a compound containing two or more isocyanate groups. Therefore, diisocyanates are a subset of polyisocyanates.

[0031] As used herein, "encapsulation" means that a coating surrounds one or more components as viewed when the one or more components are rotated 360 degrees about at least one axis. However, an enclosure may include uncoated areas as long as the coating outside of such areas is connected to and still reaches the areas when viewed about one axis.

[0032] The multiple molded part package includes two or more molded parts and a coating molded onto the surfaces of the molded parts. Although the embodiments described herein have two molded parts, it should be understood that such parts are mated together to form an assembly, and that the assembly can include more than two parts mated together, including assemblies consisting of three, four, five, six, seven, or eight parts.

[0033] The molded part can be formed, for example, by injection molding, injection compression molding, compression molding, reaction injection molding (RIM) and / or foam molding. Thermoplastics and thermosetting plastics can be used as materials, specific examples of which include, but are not limited to, polycarbonate (PC), polyesters such as polybutylene terephthalate (PBT) or polyethylene terephthalate (PET), polyamide (PA), polyethylene (PE), polypropylene (PP), polystyrene (PS), poly(acrylonitrile-co-butadiene-co-styrene) (ABS), poly(acrylonitrile-co-styrene-co-acrylate) (ASA), poly(styrene-acrylonitrile) (SAN), polyoxymethylene (POM), cyclic polyolefin (COC), polyphenylene oxide (PPO), polymethyl methacrylate (PMMA), polyphenylene sulfide (PPS), polyurethane (PUR), epoxy resin (EP), polyvinyl chloride (PVC) and blends thereof. The molded part can have any desired shape that the device can accommodate.

[0034] The molding of the molded part can be performed by injection molding using thermoplastics. Suitable thermoplastics include, but are not limited to, polycarbonate (PC), polybutylene terephthalate (PBT), polyamide (PA), polyethylene (PE), polypropylene (PP), polystyrene (PS), poly(acrylonitrile-co-butadiene-co-styrene) (ABS), poly(acrylonitrile-co-styrene-co-acrylate) (ASA), poly(styrene-acrylonitrile) (SAN), polyethylene terephthalate (PET), polyoxymethylene (POM), cyclic polyolefin (COC), polyphenylene oxide / polyamide (PPO / PA) or polyphenylene oxide / polystyrene PPO / PS blends, poly(methyl methacrylate) (PMMA), polyphenylene sulfide (PPS), thermoplastic polyurethane (TPU), epoxy resin (EP), polyvinyl chloride (PVC) and blends thereof. In certain aspects, the thermoplastic comprises a PC / ABS blend, such as BAYBLEND T85 SG from Covestro AG.

[0035] In one aspect, the components are fitted together using notch openings or the like to reduce the risk of the components sliding out of position prior to packaging. In another aspect, no adhesive or other material is applied to the surfaces where the components touch. In this embodiment, the coating surrounding the components is the only material holding the components together.

[0036] According to some aspects, after forming a plurality of molded parts, parts can be introduced in the second cavity of the same mold by opening the mold and transferring the base material into the coating mold cavity. The transfer of parts can be carried out by any of a variety of methods. The example of suitable method includes but is not limited to using a rotary table, a turntable, a sliding cavity and a graduated disk, and wherein the base material remains on the mold core and transfers by a similar method. Wherein the base material remains on the core to transfer in the example, as a further benefit, the base material position also can be accurately defined after the transfer. In some aspects, for example, with the help of a processing system, base material is removed from a cavity and placed in another cavity.

[0037] According to certain aspects of the present disclosure, a curable composition is introduced into a coating mold cavity containing a substrate to coat the surface of the substrate. The curable composition used in certain aspects comprises: (i) a first polymer component comprising a polymer containing one or more isocyanate-reactive groups; and (ii) a second polymer component comprising a polyisocyanate. In certain aspects, the curable composition can be a high-solids composition. As used herein, a "high-solids composition" means that the curable composition comprises no more than 15% by weight of volatile materials, such as organic solvents, water, etc., based on the total weight of the curable composition. In certain aspects, the curable composition comprises no more than 10% by weight of volatile materials, such as no more than 2% by weight of volatile materials or no more than 1% by weight of volatile materials. In certain aspects, the curable composition can be a 100% solids composition with a relatively low viscosity. As used herein, "relatively low viscosity" refers to a viscosity of not more than 12,000 mPa·s at 23° C. when measured according to DIN EN ISO 3219 / A3 or a viscosity of not more than 12,000 cps at 72° F. when measured according to ASTM D5125, as determined using a rotational viscometer - VISCOTESTER 550, Thermo Haake GmbH, and a hydroxyl content of 15.4-16.6% (measured according to DIN 53 240 / 2 or ASTM 7253).

[0038] Suitable polymers containing isocyanate-reactive groups include, for example, polymer polyols, such as polyether polyols, polyester polyols, and / or polycarbonate polyols, and the like.

[0039] Suitable polyether polyols include, for example, those having an Mn of 100 to 4,000 g / mol. Polyether polyols formed from repeating ethylene oxide and propylene oxide units are sometimes used, for example, those having a propylene oxide unit content of 35 to 100%, such as 50 to 100%. These can be random copolymers, gradient copolymers, or alternating or block copolymers of ethylene oxide and propylene oxide. Suitable polyether polyols derived from repeating propylene oxide and / or ethylene oxide units are commercially available and include, for example, those available from, for example, Covestro LLC, Pittsburgh, Pennsylvania (e.g., DESMOPHEN 3600Z, DESMOPHEN 1900U, ACCLAIM Polyol 2200, ACCLAIM Polyol 40001, ARCOL Polyol 1004, ARCOL Polyol 1010, ARCOL Polyol 1030, ARCOL Polyol 1070, BAYCOLL BD 1110, BAYFILL VPPU 0789, BAYGAL K55, PET 1004, POLYETHER S180).

[0040] In certain aspects, the polymer polyol comprises a polyester polyol, such as M n In some aspects, the polyester polyols have a viscosity of 700-50,000 mPa·s at 23°C and a hydroxyl number of 200-800 mg KOH / g. In some aspects, the polyester polyols can be based on aromatic carboxylic acid polyesters having an average hydroxyl functionality greater than 2, such as 3 or more, and an average hydroxyl number of 350-700 mg KOH / g, such as 450-600 mg KOH / g, and a viscosity of 1000-30,000 mPa·s at 23°C. As will be appreciated, suitable polyester polyols can be prepared by reacting a polyol with a stoichiometric amount of a polycarboxylic acid, a carboxylic anhydride, a lactone, or a polycarboxylic ester of a C1-C4 alcohol.

[0041] The polyester polyols may be derived from one or more of aromatic polycarboxylic acids or anhydrides, ester derivatives thereof, ε-caprolactone, optionally in mixture with one or more aliphatic or cycloaliphatic polycarboxylic acids or derivatives thereof.

[0042] In certain aspects, the polymer polyol comprises an aliphatic polycarbonate polyol, such as a polycarbonate diol, such as M nThose of 200-5000 g / mol, such as 150-4,500 g / mol, 300-2000 g / mol, 300-2,500 g / mol or 400-1000 g / mol, and a hydroxyl functionality of 1.5 to 5, such as 1.7 to 3 or 1.9 to 2.5. In certain aspects, such polycarbonate polyols may also have a viscosity of 2000-30,000 mPa·s, e.g., 2500-16000 mPa·s or 3000-5000 mPa·s at 23° C., when measured using a rotational viscometer—VISCO TESTER 550, Thermo Haake GmbH—in accordance with DIN EN ISO 3219 / A3, a hydroxyl content of 15.4-16.6% (measured in accordance with DIN 53 240 / 2), and / or a hydroxyl value of 40-300 mg KOH / g, e.g., 50-200 mg KOH / g or 100-200 mg KOH / g, when measured by end group analysis as is well known in the art.

[0043] The polymer containing isocyanate-reactive groups may include (i) a polyester polyol, such as a branched polyester polyol, and (ii) a polycarbonate polyol, such as a polycarbonate diol, such as a polycarbonate polyester diol, for example, those based on 1,6-hexanediol and ε-caprolactone. In certain aspects, the weight ratio of (i) to (ii) in the curable composition may be in the range of 1:10 to 10:1, such as 1:5 to 5:1, 1:4 to 4:1, 1:3 to 3:1, 1:2 to 2:1, or in some cases 1:1. In certain aspects, the polymer containing isocyanate-reactive groups (or a mixture of two or more such polymers as described above) is selected to have a relatively low viscosity at 23°C (measured according to DIN EN ISO 3219 / A.3), such as no more than 10,000 mPa·s, or in some cases no more than 9,000 mPa·s or no more than 8,000 mPa·s.

[0044] In some instances, curable composition can further comprise polyisocyanates.Suitable polyisocyanates comprise aromatic, aromatic aliphatic, aliphatic or alicyclic diisocyanates and / or polyisocyanates and mixtures thereof.In some aspects, polyisocyanates can comprise formula R (NCO) 2 diisocyanates, wherein R represents an aliphatic hydrocarbon residue with 4 to 12 carbon atoms, an alicyclic hydrocarbon residue with 6 to 15 carbon atoms, an aromatic hydrocarbon residue with 6 to 15 carbon atoms or an aromatic aliphatic hydrocarbon residue with 7 to 15 carbon atoms. Specific examples of suitable diisocyanates include, for example, xylylene diisocyanate, tetramethylene diisocyanate, 1,4-diisocyanatobutane, 1,12-diisocyanatododecane, hexamethylene diisocyanate, 2,3,3-trimethylhexamethylene diisocyanate, 1,4-cyclohexylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 4,4'-dicyclohexyl diisocyanate, 1-diisocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate), Suitable are 1,4-phenylenediisocyanate, 2,6-toluene diisocyanate, 2,4-toluene diisocyanate, 1,5-naphthalene diisocyanate, 2,4'-diphenylmethane diisocyanate or 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, α,α,α',α'-tetramethyl-m-xylylene diisocyanate or α,α,α',α'-tetramethyl-p-xylylene diisocyanate and triphenylmethane 4,4',4''-triisocyanate and mixtures thereof. Also suitable are monomeric triisocyanates, for example 4-isocyanatomethyl-1,8-octamethylene diisocyanate.

[0045] Polyisocyanate adducts containing isocyanurate, iminooxadiazinedione, carbamate, biuret, allophanate, uretdione and / or carbodiimide groups are also suitable for use in curable compositions of the present disclosure. Such polyisocyanates can have an isocyanate functionality of 3 or greater and can be prepared, for example, by trimerization or oligomerization of diisocyanates or by reaction of diisocyanates with polyfunctional compounds containing hydroxyl or amine groups. The polyisocyanate can be, for example, hexamethylene diisocyanate.

[0046] In certain examples, the curable composition may include a low-viscosity polyisocyanate having a viscosity of less than 2000 mPa·s, for example, less than 1500 mPa·s, in some cases 800-1400 mPa·s at 23° C. and 100% solids content, as measured using a rotational viscometer VISCOTESTER 550, Thermo Haake GmbH, according to DIN EN ISO 3219 / A3; an isocyanate group content of 8.0-27.0 wt %, for example, 14.0-24.0 wt % or 22.5-23.5 wt % (according to DIN EN ISO 11909); a calculated NCO functionality of 2.0 to 6.0, for example, 2.3 to 5.0 or 2.8 to 3.2; and a content of monomeric diisocyanate of less than 1 wt %, for example, less than 0.5 wt %.

[0047] Examples of these polyisocyanates include polyisocyanates containing isocyanurate groups. Cyclic and / or linear polyisocyanate molecules can be used. In order to improve weather resistance and reduce yellowing, one or more polyisocyanates in the isocyanate component can be aliphatic.

[0048] In certain aspects, the polyisocyanate comprises, consists essentially of, or can consist of a polyisocyanate containing biuret groups, such as, for example, the biuret adduct of hexamethylene diisocyanate (HDI) available from Covestro AG under the trade name DESMODUR N-100, a polyisocyanate containing isocyanurate groups, such as, for example, the polyisocyanate available from Covestro AG under the trade name DESMODUR N-3300, and / or a polyisocyanate containing urethane groups, uretdione groups, carbodiimide groups, allophanate groups, and the like.

[0049] Pre-reaction of a polyisocyanate with a hydroxyl-containing material can produce a modified polyisocyanate having a higher molecular weight and lower isocyanate content than the polyisocyanate alone. This generally results in a higher viscosity of the modified polyisocyanate. It is generally desirable for the modified polyisocyanate to have a low viscosity, such as those having a Brookfield viscosity of less than about 10,000 cps, for example, less than 5,000 cps, or in some cases less than 4,000 cps at a temperature in the range of 25°C to 70°C. Exemplary polyisocyanates include those commercially available from Covestro AG under the trade name DESMODUR N-3600, which has a viscosity of 800-1400 mPa·s at 25°C.

[0050] In certain aspects, when forming a curable composition, one or more polymers containing isocyanate-reactive groups, such as one or more polyols mentioned herein, and one or more polyisocyanates can be combined in relative amounts such that the curable composition has a ratio of isocyanate groups to isocyanate-reactive groups of 0.8 to 3.0: 1, such as 0.8 to 2.0: 1, and in some aspects 1 to 1.8: 1 or 1 to 1.5: 1. In certain aspects, the ratio can be greater than 1.2: 1, such as at least 1.3: 1 and / or up to 1.4: 1.

[0051] The curable composition used may include a catalyst for the reaction between the isocyanate-reactive groups (e.g., hydroxyl groups) and the isocyanate groups. Suitable catalysts include metal and non-metal catalysts, such as, but not limited to, amine catalysts, such as 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,4-diazabicyclo[2.2.2]octane (DABCO), or triethanolamine, and Lewis acid compounds, such as dibutyltin dilaurate, lead octoate, tin octoate, titanium and zirconium complexes, cadmium compounds, bismuth compounds such as bismuth neodecanoate, and iron compounds. In certain aspects, the catalyst may be present in the curable composition in an amount of no more than 1.0% by weight, based on the total solids content of the curable composition.

[0052] In certain examples, the curable composition may include an internal mold release agent, such as silicone, to facilitate release of the cured coating from the coating mold cavity.

[0053] When present, the internal mold release agent can be included in the curable composition in an amount of 0.1-5 weight percent, and in certain instances, can be present in an amount of 0.1-1.0 weight percent, based on the total weight of the curable composition. In certain aspects, the internal mold release agent can be present in the curable composition in an amount sufficient to provide a cured coating having a surface tension of no greater than 30 dynes / cm, for example, no greater than 25 dynes / cm, wherein the surface tension is measured using a Ramé-Hart goniometer, wherein the advancing angle is used to calculate the total solid surface energy, including polar and dispersive components, according to the OwensWendt procedure, and wherein the samples are stacked together without surface protection and the surfaces are lightly brushed to remove dust prior to analysis.

[0054] The curable composition may further comprise, for example, any customary auxiliaries and additives in coatings technology, such as defoamers, thickeners, pigments, dispersing aids, catalysts, anti-skinning agents, anti-settling agents and / or emulsifiers.

[0055] In certain aspects, the step of coating the substrate can be performed at an elevated pressure, for example, greater than 500 pounds per square inch gauge (psi), in certain instances at least 1000 psi, and in other instances at least 1600 psi. In certain instances, the elevated pressure can be from 1500 psi to 3000 psi, and in certain other instances from 1600 psi to 2800 psi.

[0056] This article describes a tool with a mold cavity in which two or more molded parts are placed. In order to form a package, after the parts are placed in the cavity, a coating is applied around the two or more molded parts. The coating can be applied by injecting the curable composition into the gap between the surface of the molded part and the inner wall of the coating mold cavity under elevated pressure. The pressure can be increased in any way that provides a suitable level for the coating mold cavity. For example, the coating mold cavity can be pressurized by an external pressure device such as a fixture (as described in more detail below) to fill before the pot life of the curable composition is reached. Pressure can also help prevent bubbles from forming at the flow front of the curable composition.

[0057] Can complete the injection of curable composition in the coating mold cavity by one or more injection points, make the gap between the surface of molding and the inwall of coating mold cavity be filled with curable composition.For the best injection of curable composition, can suitably select the position of injection point in a manner well known to those skilled in the art.In some aspects, the size of adjustment gap makes curable composition be injected into the gap and after solidification, the dry coating thickness of the curable composition of solidification is 50 microns to 4000 microns, is 1000 to 2000 microns in some instance.

[0058] The coating mold cavity can be designed to provide controlled displacement of air present in the coating mold cavity and remove air through the parting line or vents during the injection process. Known computer programs, such as Moldflow from Autodesk Inc., can be used to provide controlled air displacement. In certain aspects, the mixture is injected into the coating mold cavity at a flow rate of 2-40 g / s, a line pressure of 500-3000 psi (34-206 bar), and a temperature of 120-200°F (49-52°C), depending on viscosity (higher viscosity mixtures require higher temperatures). In certain examples, the mixture is injected into the coating mold cavity at a flow rate of less than 8 g / s.

[0059] Coating can be performed using a RIM process with a single cavity or multiple cavities. The RIM process can be advantageous in that the components of the curable composition are combined just prior to injection into one or more coating mold cavities. In certain aspects, this is accomplished by feeding a first polymer component comprising an isocyanate-reactive resin (as described herein) and a second polymer component comprising a polyisocyanate (as described herein) from a RIM apparatus into an impingement mixing head, hereinafter referred to as a mixing head, where the polymer components are mixed prior to injection into the coating mold cavities. Within the mixing head, the components of the curable composition are impacted together under elevated pressure to induce mixing. In certain aspects, the elevated pressure is at least 500 psi, for example, at least 1000 psi, and in other examples, at least 1600 psi. For example, the elevated pressure can range from 1500 psi to 3000 psi, and in other examples, from 1600 psi to 2800 psi. Typically, to achieve these pressures, each component is fed into the mixing head through a small diameter orifice, for example, with a diameter of 0.1 mm to 1.0 mm.

[0060] The components of curable composition can be mixed by a countercurrent mixing head, a static mixer or an active mixer (active mixer) that raises the pressure. After mixing, the curable composition can enter the channel (e.g., runner, sprue, etc.) in the mold, which guides the curable composition flow into the coating mold cavity. Due to the resistance of the curable composition entering the coating mold cavity and displacing air, the filling of the coating mold cavity produces back pressure. Back pressure can be affected by the length that the curable composition must travel from the injection point to the point farthest from the gate in the mold and the cross-sectional area along this length. Reducing the cross-sectional area (e.g., reducing the coating thickness) while maintaining the same travel length produces higher back pressure because the curable composition is more resistant to flowing through a smaller cross-sectional area.

[0061] As the curable composition begins to cure into a cured coating on the surface of the molded part, the viscosity of the curable composition may increase, and therefore, back pressure increases as the coating becomes more resistant to flow.

[0062] Figure 1 A front view of a first molded part 1 is shown, which has a raised element 2 , a support base 3 , a notch element 4 and a surface 5 . Figure 2 A rear view of the first molded part 1 is shown. Figure 3 A front view of the second moulding 6 is shown, which has a raised element 7 , a support base 8 , a notch element 9 and a surface 10 . Figure 4 Shown is a rear view of the second moulding 6. The notch element makes it easier to see where the parts fit together and also prevents sliding of the parts when they fit together before packaging.

[0063] Figure 5 A front view of a package 11 is shown having a raised element 12 , a coating surface 13 and a support base 14 . Figure 6 Shown Figure 5 Rear view of the package 11. The raised element 12 and the support base 14 are not coated. Figure 5 and 6 As shown in FIG, the surface of the encapsulation is coated in a manner that surrounds the molded plastic part. Encapsulation 11 can be rotated about axis AA, and at each angle during a complete rotation, the molded part can be seen coated on at least a portion of its surface. It is worth noting that the entire portion does not need to be coated, but rather the coating surrounds at least a portion at all angles around an axis. In this way, the coating continuously wraps around the entire plastic part assembly to provide strength to the encapsulation.

[0064] Figure 7 The figure is a perspective view of a packaging tool 20 for forming a packaging of two molded parts. The packaging tool 20 includes a cover 21 and a base 22. The components of the coating enter the tool 20 through an opening 24. An adapter 23 may be used, to which a mixing head (not shown) may be connected for mixing the components of the coating before it enters the opening 24. The tool 20 further includes a handle 25 for removing the cover 21. A water line connection 26 is also shown, which can be used to heat the tool 20. Although the connection is referred to as a water line connection, other heating fluids can be used instead of water.

[0065] Figure 8 is a perspective view of the base 31 of the encapsulation tool. A molded part 30 has been placed within a coating mold cavity 37. A gap (not shown) exists between the molded part 30 and the coating mold cavity 37, into which the coating composition flows. As mentioned above, the molded part 30 may include raised elements. Such elements may be raised to a level that prevents those portions from being coated during the encapsulation process. An adapter 32 is shown, to which a mixing head (not shown) can be connected for mixing the coating components before they enter the channel 36. Also shown are water line connections 33 and 34 for heating the base 31. Also shown are support pins 35, which are used to ensure proper placement of the lid.

[0066] Figure 9 It is from Figure 8A perspective view from the opposite direction is shown. The base 45 of the encapsulation tool is shown. A molded part 54 has been placed within the coating mold cavity. Mold hanger inserts 51 and connectors 52 secure the molded part 54 in place during the encapsulation process, during which coating is applied to the coating surface 53 of the molded part 54. In one embodiment, the coating surface 53 can form a seal around a portion of the molded part 54, leaving space for the non-coated surface 55 to be uncoated. In other embodiments, the coating can flow around the molded part 54 to form an encapsulated part without any non-coated surfaces (not shown). The non-coated surfaces 55 can be raised so that the coating material will bypass such surfaces rather than coating them when injected into the mold. In other embodiments, the non-coated surfaces may not be raised, but rather the mold cavity surface may be raised in those areas to contact the non-coated surfaces, so that the liquid coating material will also bypass them.

[0067] An adapter 46 is shown to which a mixing head (not shown) may be connected for mixing the components of the paint before it enters opening 47. Also shown are water line connections 48 and 49 for the heated base 45. Also shown are support pins 50 for ensuring correct placement of the cover.

[0068] In this way, the molded part can be encapsulated without the use of any silicone or other materials used to bond two or more parts together. There is also no external support structure to hold the parts together. Instead, the parts are held together solely by the coating that forms the encapsulation.

[0069] In certain aspects, an external mold release agent is present on the surface of one or both of the substrate and the coating mold cavity. In certain aspects, a coating comprising, for example, electroless nickel and polytetrafluoroethylene (PTFE) can be used as an external mold release agent. Such a coating is commercially available from Poly-Plating, Inc. under the trade name POLY-OND.

[0070] A curable composition can be supplied to the coating mold cavity under elevated pressure to form a curable coating on the substrate. The curable coating can be exposed to curing conditions of elevated temperature and external mold pressure (e.g., which maintains elevated pressure within the coating mold cavity) to cure the curable coating. Suitable curing conditions include a mold temperature, for example, 62°C to 105°C, and in some instances, 75°C to 105°C. In certain aspects, the curing time, such as the reaction time, is at least 10 seconds, and in some instances, can be 10-90 seconds. In certain aspects, the curing time can be at least 70 seconds, and in other instances, can be 70 to 120 seconds. In certain aspects, the curing time can be no more than 5 minutes. In another aspect, the curing time can be optimized to match the curing time of the molded plastic substrate. In certain aspects, the pressure in the coating mold cavity can be reduced from the elevated pressure to ambient pressure (e.g., 1 atmosphere) before or in response to opening the mold.

[0071] As used herein, "external mold pressure" refers to the externally applied pressure exerted on opposing surfaces of the mold (wherein the coating mold cavity is located) when the opposing surfaces of the mold are pressed together. The source of such pressure can be a clamp, plunger, or other device. The tonnage of the external mold pressure should be sufficient to prevent flashing of the coating. In some aspects, the external mold pressure remains relatively constant during the coating curing process.

[0072] In-mold processes can also be performed in molds with more than two cavities. Cavities can be used to apply multiple coatings sequentially. For example, a first coating can be applied in a first cavity, a second coating can be applied in a second cavity, and so on, until the desired number of coatings has been applied. In some aspects, one coating applied can have specific properties that differ from one or more other coatings. In another aspect, multiple molded plastic substrates can be produced in parallel, each in a first cavity, and then each in a second cavity, coated in parallel.

[0073] Using the above features (e.g. ， The mold can be appropriately configured with a secondary mixer, a dump well, and / or multiple channels to provide a substantially mixed curable composition for coating a substrate with a curable coating such that when the coating mold cavity is opened, the cured coating is substantially free of surface defects and / or tack defects and, in certain aspects, has a dry coating thickness of 50 microns to 200 microns, and in some examples, 80 microns to 100 microns.

[0074] Injection molding equipment can facilitate the production of substrates from thermoplastics or thermosetting plastics using injection molding methods. Suitable injection molding equipment is known to those skilled in the art. They include a standard injection molding machine structure, which includes a plasticating unit (e.g., heater, screw, etc.) for processing the plastic, and a closing unit (e.g., clamp unit) responsible for the movement, opening, and closing of the substrate mold.

[0075] The coating injection device can help produce the coating on the substrate. The coating injection device can be connected to a channel to fill the coating mold cavity with the curable composition and coat the substrate. Suitable coating injection devices may include one or more storage containers for the polymer components, an agitator, a feed pump, a temperature control device, a feed line, and a mixing device (e.g., a mixing head).

[0076] One advantage of the present invention is that the package uses less coating material and other adhesive materials than previously used. Not only is there no silicone or other adhesives or structures holding the component and package together, but the method applies the coating only to those areas selected to create the package. Compared to other methods, such as immersion coating, material waste is minimized. Furthermore, the use of raised or uncoated surfaces allows for the use of less coating material when preparing the package.

[0077] The encapsulations described herein can be used to form a variety of industrial and commercial products and are suitable, for example, for forming tamper-evident seals for materials that can be stored within molded parts. Further applications include automotive interior components such as pillar liners, trim, glove box lids, covers, lamp housings, instrument panels, and air delivery system components. Furthermore, the encapsulations can be used in industrially produced plastic components such as housings for electrical equipment, computer devices, mobile phones, medical devices, and household goods.

[0078] Aspects of the invention include, but are not limited to, the following numbered items.

[0079] 1. A method for in-mold coating, comprising:

[0080] introducing a first plastic molded part into a cavity of a mold;

[0081] introducing a second plastic molded part into the cavity, wherein the first molded part and the second molded part mate together to form an assembly having an exterior surface;

[0082] introducing a coating composition into the cavity; and

[0083] curing the coating on the outer surface of the assembly,

[0084] wherein the coating flows in a gap between the outer surface of the assembly and the cavity, and

[0085] The coating flows 360 degrees around the outer surface of the assembly so that when the coated assembly is rotated 360 degrees about an axis, the coating can be seen applied to a portion of the outer surface of the assembly at any angle about the axis.

[0086] 2. The method according to 1, wherein the first plastic molded part and the second plastic molded part are held together only by the cured coating and not by any other adhesive or structure.

[0087] 3. A package comprising:

[0088] a first plastic molded part;

[0089] a second plastic molded part, wherein the first molded part and the second molded part mate together to form an assembly having an exterior surface;

[0090] a cured coating on the outer surface of the assembly,

[0091] wherein the coating flows 360 degrees around the outer surface of the assembly so that when the coated assembly is rotated 360 degrees about an axis, the coating can be seen applied to a portion of the outer surface of the assembly at any angle about the axis, and

[0092] The package does not include any other adhesive or structure.

[0093] 4. A method or package as claimed in any preceding claim, wherein the first plastic moulding comprises polycarbonate, and optionally the second plastic moulding comprises polycarbonate.

[0094] 5. The method or package of any of the above, wherein the coating composition comprises (i) a first polymer component comprising a polymer containing one or more isocyanate-reactive groups, preferably a polyether polyol or a polycarbonate polyol, and (ii) a second polymer component comprising a polyisocyanate, preferably a diisocyanate.

[0095] 6. The method or package of any preceding claim, wherein the second polymer component comprises a polyisocyanurate.

[0096] 7. The method or package of any preceding claim, wherein the second polymer component comprises biuret groups.

[0097] 8. The method or package of any preceding claim, wherein the coating composition further comprises an internal mold release agent.

[0098] 9. The method or package of any preceding claim, wherein the first plastic moulding and the second plastic moulding comprise one or more indentations.

[0099] 10. A method or package as claimed in any preceding claim wherein the outer surface of the assembly comprises one or more portions which are uncoated and one or more other portions which are coated.

Claims

1. A method for in-mold coating, comprising: introducing a first plastic molded part into a cavity of a mold; introducing a second plastic molded part into the cavity, wherein the first molded part and the second molded part mate together to form an assembly having an exterior surface; introducing a coating composition into the cavity, wherein the coating composition flows in a gap between the outer surface of the assembly and the cavity; as well as adjusting the size of the gap and curing the coating composition on the outer surface of the assembly at a mold temperature of 62° C. to 105° C. and an elevated pressure of 1500 psi to 3000 psi so that the dry coating thickness of the coating composition is 50 microns to 200 microns, wherein the first plastic molded part and the second plastic molded part are held together only by the cured coating composition and not by any other adhesive or structure, wherein the coating composition comprises (i) a first polymer component comprising a polymer containing one or more isocyanate-reactive groups, and (ii) a second polymer component comprising a polyisocyanate, and wherein the coating composition flows 360 degrees around the exterior surface of the assembly such that when the coated assembly is rotated 360 degrees about an axis, the coating composition can be seen applied to a portion of the exterior surface of the assembly at any angle about the axis, and wherein the exterior surface of the assembly includes one or more portions that are uncoated and one or more other portions that are coated.

2. The method according to claim 1, wherein At least one of the first plastic molded part and the second plastic molded part comprises polycarbonate.

3. The method of claim 1, wherein the first polymer component is a polyether polyol or a polycarbonate polyol. 4 . The method according to claim 1 , wherein the second polymer component comprises one selected from the group consisting of a diisocyanate group, a polyisocyanurate group, and a biuret group.

5. The method of claim 1, wherein the coating composition further comprises an internal mold release agent.

6. The method of claim 1, wherein the first plastic molding and the second plastic molding include one or more notches.

7. A package comprising: a first plastic molded part; a second plastic molded part, wherein the first molded part and the second molded part mate together to form an assembly having an exterior surface; a cured coating on the outer surface of the assembly having a dry coating thickness of 50 microns to 200 microns and curing conditions comprising a mold temperature of 62° C. to 105° C. and an elevated pressure of 1500 psi to 3000 psi, wherein the coating flows 360 degrees around the outer surface of the assembly such that when the coated assembly is rotated 360 degrees about an axis, the coating appears to be applied to a portion of the outer surface of the assembly at any angle about the axis, wherein the outer surface of the assembly comprises one or more portions that are uncoated and one or more other portions that are coated, wherein the coating composition comprises (i) a first polymer component comprising a polymer comprising one or more isocyanate-reactive groups, and (ii) a second polymer component comprising a polyisocyanate, and wherein the package does not include any other adhesive or structure.

8. The package according to claim 7, wherein: At least one of the first plastic molded part and the second plastic molded part comprises polycarbonate.

9. The package of claim 7, wherein the first polymer component is a polyether polyol or a polycarbonate polyol. 10 . The package according to claim 7 , wherein the second polymer component comprises one selected from the group consisting of a diisocyanate group, a polyisocyanurate group, and a biuret group.

11. The package of claim 7, wherein the coating composition further comprises an internal mold release agent. 12 . The package of claim 7 , wherein the first plastic molding and the second plastic molding include one or more notches.

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