Release agent for polyurethane articles

Abstract

The present invention relates to an aqueous mold release agent for producing polyurethane articles, particularly molded polyurethane foam articles, comprising an unsaturated polymer and a Norrish type 1 and / or Norrish type 2 photoinitiator, wherein the unsaturated polymer comprises polybutadiene, polyisoprene, a copolymer of butadiene and isoprene, or a combination thereof. The present invention further relates to a process for producing a molded polyurethane article, comprising applying the aqueous agent to a mold, and to the use of the aqueous mold release agent for producing a molded polyurethane article.

Description

[Technical Field]

[0001] The present invention relates to an aqueous release agent for the manufacture of polyurethane articles, particularly molded polyurethane foam articles. The aqueous agent comprises an unsaturated polymer and a Norrish type 1 or Norrish type 2 photoinitiator. The present invention further relates to a process for manufacturing a molded polyurethane article, comprising the steps of applying the aqueous agent to a mold and, after removing the article from the mold, irradiating at least a portion of the surface of the article with UV light. The present invention also relates to the use of the aqueous release agent for the manufacture of molded polyurethane articles.

[0002] Background technology Polyurethane is often used as a main component of cushions, for example, in the automotive industry. In this application, a small amount of water is added to a reaction mixture containing a polyol and an isocyanate monomer, resulting in the formation of carbon dioxide and foaming of the resulting polymer. The mixture is poured into a mold to form the desired object to be used as a filler. Polyurethane is also known in the art to exhibit strong adhesion to other materials, and therefore, polyurethane is used in a wide range of adhesive compositions. However, this property of polyurethane is a significant disadvantage when preparing molded polyurethane articles, as the resulting polyurethane articles adhere to the mold, making it almost impossible to remove the article without damaging the molded product.

[0003] Therefore, the use of a release agent is necessary. The release agent is usually applied to the mold by spraying the agent directly onto the mold before forming the article. Once the polyurethane article is molded, the polyurethane adheres to the release agent, but the release agent exhibits very low adhesion to the mold, allowing the article to be easily removed from the mold without damaging it.

[0004] Such mold release agents may contain waxes, soaps, oils, or polymers as active ingredients that reduce adhesion to the mold. Traditionally, solvent-based mold release agents, i.e., those containing volatile organic solvents as a carrier, have been commonly used. These solvent-based agents, especially when based on wax as the release agent, have the advantage that once the solvent evaporates, a dry surface of the molded article is obtained, which is suitable for further processing. Depending on the intended use of the molded article, further processing may include, for example, the application of adhesives, lacquers, or coatings. However, the use of volatile organic solvents has become undesirable due to their environmental impact and the cost of removing solvent vapors from exhaust to meet emission limits.

[0005] To overcome this problem, water-based mold release agents have been developed. Such agents, for example, as disclosed in European Patent Application Publication No. 0320 833A2, use water as a carrier and low molecular weight polybutadiene or polyisoprene as the active ingredient. Other water-based mold release agents, as disclosed in European Patent Application Publication No. 0460 783A1, utilize oil, wax, or fatty esters as the active release agent. Water-based mold release agents have the advantage of producing significantly reduced waste. However, while water-based mold release agents with wax as the active ingredient tend to adhere to the mold, those with polybutadiene or polyisoprene as the active release ingredient leave a residue on the surface of the molded article, which is very useful for removing the article from the mold, but undesirable for further processing of the article because, for example, coatings, adhesives, or lacquers do not adhere well to the sticky, wet surface. The effects of different combinations of carrier and active release ingredient are shown in Table 1 below:

[0006] [Table 1]

[0007] U.S. Patent Application Publication No. 2005 / 0239935 discloses a release agent comprising an aqueous carrier, an unsaturated polymer, and further a Norrish type 1 photoinitiator and / or a Norrish type 2 photoinitiator. The release agent may be included in a radiation-curable composition to facilitate the release of polymer shims from a master mold and to extend the life of the master mold.

[0008] International Publication No. 01 / 98817 discloses a radiation-curable carrier system suitable for forming an ink composition containing one or more radiation-curable oligomers or monomers having at least one functional group that can be oligomerized when exposed to photochemical radiation. The photoinitiator used in this ink composition is preferably a free radical photoinitiator such as Norrish type 1 and Norrish type 2 photoinitiators.

[0009] As a result, there is a need for improved mold release agents that combine the advantages of solvent-based and water-based release agents without producing volatile organic solvents.

[0010] Summary of the Invention Therefore, an object of the present invention is to provide an improved water-based release agent for polyurethane-based articles, which allows for easy removal of the article from the mold, but can also be easily cured to provide a surface ready for further processing of the article.

[0011] It was found that when Norrish type 1 or Norrish type 2 photoinitiators are added to a water-based release agent, the curing process can be initiated by irradiating the surface of the resulting molded polyurethane article with photochemical radiation. As a result, the properties of the agent adhering to the surface of the polyurethane article can be changed from a sticky, wet state to at least a waxy state, or even a solid and dry state, making the surface suitable for further processing.

[0012] Accordingly, the present invention relates to a mold release agent for producing a molded polyurethane article comprising an aqueous carrier, an unsaturated polymer, and a Norrish type 1 and / or Norrish type 2 photoinitiator such as an acetophenone type 1 photoinitiator, a benzophenone-based type 2 photoinitiator, or a phosphine oxide photoinitiator, wherein the unsaturated polymer comprises polybutadiene, polyisoprene, a copolymer of butadiene and isoprene, or a combination thereof.

[0013] The present invention further relates to a process for manufacturing a molded polyurethane article, characterized by comprising the steps of applying the aqueous release agent to a mold, and, after removing the article from the mold, irradiating at least a portion of the surface of the article with photochemical radiation having a wavelength of 100 nm to 800 nm.

[0014] Furthermore, the present invention relates to the use of the aqueous mold release agent for the manufacture of molded polyurethane articles.

[0015] Modes for carrying out the invention Any numerical values ​​disclosed herein inherently include a specific error that inevitably arises from the standard deviation observed in each test measurement.

[0016] Furthermore, it should be understood that any numerical range listed herein is intended to include all subranges contained within it. For example, the range "1 to 10" is intended to include all subranges between (and including) the listed minimum value of 1 and the listed maximum value of 10, i.e., all subranges having a minimum value of 1 or greater and a maximum value of 10 or less.

[0017] The term "curing" refers to the process by which a composition or drug solidifies or hardens through a chemical reaction, either by itself or with a crosslinking agent. Correspondingly, the term "cured" refers to the state of a composition or drug that has changed from a liquid or fluid to at least a highly viscous and sticky state, or even a solid and dry state.

[0018] The term "polymer" refers to both homopolymers and copolymers, but copolymers can include random, block copolymers, and graft copolymers.

[0019] The Norrish type 1 or Norrish type 2 photoinitiators (photoinitiators) in the release agents according to the present invention are initiators that do not require a co-initiator to generate free radicals when irradiated with photochemical radiation corresponding to their absorption maximum. When irradiated with photochemical radiation having a wavelength close to their absorption maximum, the photoinitiators undergo uniform α-cleavage, generating several highly reactive radicals. Those skilled in the art will recognize that the photoinitiators include monomer or polymer derivatives of acetophenone, acylphosphine oxide, benzoin ether, benzophenone, and thioxanthone, each containing an unsubstituted compound, i.e., a compound containing an α-phenylketone substructure.Examples of such derivatives include acetophenone, anisoin, benzoin, benzophenone, benzoin ethyl ether, benzoin isobutyl ether, benzoin methyl ether, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 4-benzoylbiphenyl, 2-benzyl-2-(dimethylamino)-4'-morpholinobtylophenone, 4,4'-bis(diethylamino)benzophenone, 4,4'-bis(dimethylamino)benzophenone, 2,2-diethoxyacetophenone, 2,2-dimethyl-2-hydroxyacetophenone, 2,2-dimethyl-2-aminoacetophenone, 2,2-diethyl-2-hydroxyacetophenone, 2,2-diethyl-2-aminoacetophenone, 2,2-diethoxy-2-hydroxyacetophenone, 2,2-diethoxy- It may contain 2-aminoacetophenone, 4,4'-dihydroxybenzophenone, 2,2-dimethoxy-2-phenylacetophenone, 4-(dimethylamino)benzophenone, 2,5-dimethylbenzophenone, 3,4-dimethylbenzophenone, 2-hydroxy-2-methyl-4'-alkylpropiophenone, 4'-ethoxyacetophenone, 3'-hydroxyacetophenone, 4'-hydroxyacetophenone, 3-hydroxybenzophenone, 4-hydroxybenzophenone, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methylpropiophenone, 2-methylbenzophenone, 3-methylbenzophenone, methylbenzoyl formate, 2-methyl-4'-(methylthio)-2-morpholinopropiophenone, and 4'-phenoxyacetophenone. The selection of photoinitiators is described in “A Compilation of Photoinitiators Commercially available for UV today” (K. Dietliker, SITA Technology Ltd, London 2002).

[0020] Examples of photoinitiators that can be used in the present invention are selected from α-hydroxyacetophenone, α-aminoacetophenone, acylphosphine oxide and benzophenone, more preferably α-hydroxyacetophenone, for example a photoinitiator selected from hydroxyacetophenone, for example α-hydroxyacetophenone having the following formula. [Chemical formula] (In the formula, R 1 is a linear or branched C8-C 20 alkyl, and R 2 and R 3 are independently C1-C3 alkyl or ethoxy). Most preferably, R 1 is linear or branched C 10 -C 13 alkyl, and / or R 2 and R 3 are methyl).

[0021] Acetophenone-based or benzophenone-based type 1 photoinitiators can be present in the release agent of the present invention in an amount of 0.01% to 20% by weight, preferably 1% to 10% by weight, based on the total weight of the unsaturated polymer.

[0022] The release agent further contains an unsaturated polymer. Therefore, the polymer backbone contains at least one non-conjugated C-C double bond per repeating unit. Therefore, the polymer includes polybutadiene, polyisoprene, a copolymer of butadiene and isoprene, or a combination thereof. Due to the above-mentioned strong adhesive properties of polyurethane, the unsaturated polymer preferably does not include a copolymer of polyurethane and polybutadiene and / or polyisoprene. The polymer may be solid, liquid, or fluid, but liquid and / or fluid polymers are preferred. As a result, the polymer preferably has a molecular weight of at least 500 g / mol, more preferably 1,000 g / mol to 10,000 g / mol, even more preferably 1,500 g / mol to 7,500 g / mol, and most preferably 2,000 g / mol to 5,000 g / mol.

[0023] The unsaturated polymer may be present in the release agent of the present invention in an amount of 2% to 50% by weight, preferably 7% to 20% by weight, more preferably 8% to 15% by weight, and most preferably 9% to 12% by weight, based on the total weight of the release agent. The agent of the present invention may contain other polymers other than the unsaturated polymer defined above, but the agent preferably contains one or less polymers in addition to the unsaturated polymer.

[0024] The release agent of the present invention contains an aqueous carrier. Therefore, the release agent may contain at least 30% by weight, preferably at least 45% by weight, more preferably at least 60% by weight, and most preferably at least 70% by weight of water. The agent of the present invention may contain, for example, 30% to 80% by weight of water. The agent of the present invention may also substantially not contain an organic solvent such as mineral oil, long-chain (more than C5) alkane, halogenated alkane, short-chain alcohol containing polyol, liquid aryl compound, ether, ester, liquid sulfoxide, or liquid lactam. Substantially not containing in this context means that, despite efforts to exclude such a solvent from the agent of the present invention, such a solvent may be present in the agent of the present invention in an amount of up to 5% by weight, preferably up to 2.5% by weight, more preferably up to 1% by weight, and most preferably up to 0.1% by weight, based on the total weight of the release agent.

[0025] The mold release agent according to the present invention may further contain any additional components commonly used in mold release agents. Such components may include thickeners, foam stabilizers such as polysiloxane-polyether-polymers, emulsifiers, biocides, quaternary ammonium compounds, catalysts, particularly catalysts for forming polyurethanes, and dispersion aids. The aforementioned catalysts may include, for example, tin salts (such as tin salts of organic acids), organotin compounds (such as dimethyltin dilaurate or dibutyltin dilaurate), bismuth(III) compounds (such as bismuth(III) salts and bismuth(III) complexes of organic and inorganic acids), and amine catalysts. The aforementioned compounds may be present in the mold release agent of the present invention in a total amount of up to 15% by weight, preferably up to 10% by weight, based on the total weight of the mold release agent.

[0026] Suitable emulsifiers may include ionic and nonionic surfactants. Ionic surfactants may include, for example, (ethoxylated) aliphatic amines protonated with acetic acid, preferably (ethoxylated) aliphatic amines containing 16 to 18 carbon atoms. Nonionic surfactants may include ethoxylated and / or propoxylated fatty alcohols, or (ethoxylated) fatty amines. Among these emulsifiers, a narrow range of ethoxylated aliphatic alcohols and aliphatic amines is preferred. Particularly preferred ethoxylated aliphatic alcohols include aliphatic alcohols having 4 to 10 EO, more preferably 6 to 10 EO, for example, aliphatic alcohols having 8 EO. If present, the emulsifier may be present in the release agent according to the present invention in a total amount of 2% to 6% by weight, preferably 3% to 5% by weight, based on the total weight of the release agent.

[0027] The present invention further relates to a process for manufacturing molded polyurethane articles. This process includes, as essential steps, (i) applying the above-mentioned aqueous release agent to a mold, and (ii) removing the article from the mold and then irradiating at least a portion of the surface of the article with photochemical radiation having a wavelength of 100 nm to 800 nm.

[0028] The aqueous release agent according to the present invention can be applied to an open mold, particularly by spraying, brushing, or by applying with a wipe impregnated with the agent of the present invention. Spraying can be performed using any technique known in the art, for example, using an airless spray gun.

[0029] Articles may be formed by any molding technique and by any molding process known in the art using any composition useful for forming polyurethane articles, in particular a composition comprising at least one diol and at least one diisocyanate.

[0030] Before or immediately after spraying, the mold may be heated to 40°C to 80°C to evaporate at least a portion of the aqueous carrier. A reactive composition containing a polyol, polyisocyanate, and any further optional additives such as catalysts, foam stabilizers, and propellants may then be injected into the mold. After the polyurethane composition has cured, the mold may be opened and the formed polyurethane article removed from the mold.

[0031] As part of the process of the present invention, at least a portion of the molded article is then irradiated with photochemical radiation having a wavelength of 100 nm to 800 nm to cure the release agent present on the surface of the molded article. The photochemical radiation source may be selected according to the required maximum emission value, which depends on the absorption maximum of the photoinitiator used. Suitable UV light sources are known in the art and include mercury vapor lamps, gas discharge lamps, and ultraviolet LEDs and lasers. Preferably, the photochemical radiation may have a wavelength of 100 nm to 450 nm, more preferably 200 nm to 400 nm. The radiation source may have an output of 20 to 2000 W, preferably 40 to 400 W.

[0032] The irradiation process may be carried out at 20°C to 100°C, preferably 20°C to 60°C.

[0033] At least a portion of the surface of the molded article may be irradiated for 1 to 300 seconds.

[0034] Only a predetermined portion of the entire surface of the article may be irradiated. This depends on the desired surface properties of the molded article.

[0035] The present invention further relates to the use of the aforementioned mold release agent in the manufacture of molded polyurethane articles. Such articles may preferably be molded polyurethane foam articles.

[0036] After the curing step of the process of the present invention, these articles may be covered with textiles, fabrics, fleece, leather, or other materials for covering automobile seats, furniture, or mattresses.

[0037] Examples Several release agents with the compositions shown in Table 2 below were prepared: [Table 2]

[0038] Before manufacturing the foam, the mold was treated with the water-based agent of the present invention described above.

[0039] Polyurethane foam was manufactured in the laboratory as so-called molded foam according to two foam formulations. The foam was manufactured at 22°C and an air pressure of 762 mmHg according to the following specifications: the foam was manufactured using a heated aluminum mold measuring 40 cm × 40 cm × 10 cm. The molding temperature was 60-70°C.

[0040] The test was conducted using two different systems in two different formats: Methylenediphenyl isocyanate-based polyurethane: Polyol: Elastoflex W5515 / 146 (BASF); Isocyanate: Methylenediphenyl isocyanate, Toluene diisocyanate-based polyurethanes: Polyols: See Table 3; Isocyanates: DESMODUR T80 (2,4- and 2,6-toluene diisocyanate, Covestro)

[0041] [Table 3]

[0042] It was found that each article could be easily removed from the mold without damaging it. Furthermore, it was observed that each molded article had a sticky, wet surface after being removed from the mold.

[0043] After demolding, a 17cm x 5cm x 1cm (length, width, height) foam pattern was irradiated for 1 to 300 seconds with a UV lamp having a wavelength of 100-400nm and an output of 40-120W, and the solidification of the material on the surface of the molded article was observed during this time.

[0044] Next, each molded article was subjected to a peel strength test (Method A) and an axial detachment test (Method B) using FT 7999 double-coated nonwoven adhesive foil (Avery Dennison). Prior to testing, the test specimens were conditioned at room temperature for 24 hours. The test conditions were as follows:

[0045] Method A: The minimum size of the foam test specimen is 200 x 50 x 10 mm, and the adhesive tape is 200 x 50 mm. The test must be performed on three test specimens 10 minutes after preparation, and on three other test specimens 72 hours after preparation.

[0046] The protective liner was removed from the adhesive band test specimen, the band was aligned with the foam pad, and a pressure roller (5 kg) was rolled four times over the specimen to ensure mutual bonding. The foam was secured with an upper clamp, and the tape was secured with a lower clamp. The lower clamp was tensile at a 180-degree angle at 100 mm / min while applying a preload of 0.1 N until adhesive failure occurred. The results are given as the arithmetic mean of both systems described above, with six measurements per foam system.

[0047] Method B: Minimum size for foam test specimen: 100 x 50 x 25 mm; adhesive tape: 100 x 25 mm.

[0048] Adhesive tape was applied to a foam test specimen with a 50mm overlap. The foam was secured with an upper clamp, and the tape was secured with lower clamps (25mm each). The starting distance between the clamps was 100mm. The dynamometer was started at a speed of 100mm / min and continued until adhesive failure occurred. The results are given as the arithmetic mean of both systems described above, with three measurements per foam system.

[0049] The results are shown in Table 3 below. Form A is a form prepared according to the embodiment of the present invention after irradiation. Form B is a form prepared according to the embodiment of the present invention before irradiation. Form C is a form prepared using a conventional solvent-based release agent and has not been irradiated.

[0050] [Table 4]

[0051] These results show that the mold release agent of the present invention allows molded articles to be easily removed from the mold without damaging the articles. Furthermore, it allows articles to be easily cured, making the surface of the molded article suitable for further processing, such as the application of adhesives, coatings, or lacquers.

Claims

1. A mold release agent for producing a molded polyurethane article, comprising an aqueous carrier, an unsaturated polymer, and further a Norrish type 1 photoinitiator and / or a Norrish type 2 photoinitiator, wherein the unsaturated polymer comprises polybutadiene, polyisoprene, a copolymer of butadiene and isoprene, or a combination thereof.

2. The release agent according to claim 1, wherein the main chain of the unsaturated polymer contains at least one non-conjugated C-C double bond per repeating unit.

3. The release agent according to claim 1 or 2, wherein the unsaturated polymer is present in an amount of 2% to 50% by weight, preferably 7% to 20% by weight, more preferably 8% to 15% by weight, and most preferably 9% to 12% by weight, based on the total weight of the release agent.

4. The release agent according to any one of claims 1 to 3, wherein the polymer has a molecular weight of at least 500 g / mol, preferably 1,000 to 10,000 g / mol, and more preferably 2,000 g / mol to 5,000 g / mol.

5. A release agent according to any one of claims 1 to 4, comprising a Norrish type 1 photoinitiator.

6. The release agent according to claim 5, wherein the Norrish type 1 photoinitiator is an α-hydroxyacetophenone-based Norrish type 1 photoinitiator.

7. The release agent according to any one of claims 1 to 6, wherein the Norrish type 1 photoinitiator and / or the Norrish type 2 photoinitiator are present in an amount of 0.01% to 20% by weight, preferably 1% to 10% by weight, based on the total weight of the unsaturated polymer.

8. A process for manufacturing a molded polyurethane article, comprising applying an aqueous release agent according to any one of claims 1 to 7 to a mold, wherein the process includes a step of irradiating at least a portion of the surface of the article with photochemical radiation having a wavelength of 100 nm to 800 nm after removing the article from the mold.

9. The process according to claim 8, wherein at least a portion of the surface of the article is irradiated for 1 second to 300 seconds.

10. The process according to claim 8 or 9, wherein the photochemical light source has an output of 20 W to 2000 W.

11. The process according to any one of claims 9 to 10, wherein the photochemical radiation has a wavelength of 100 nm to 450 nm.

12. Use of an aqueous release agent according to any one of claims 1 to 7 in the manufacture of a molded polyurethane article.

13. The use according to claim 12, wherein the molded polyurethane article is a molded polyurethane foam article.

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