Release agent

Abstract

The objective of this invention is to provide a release agent that provides good release properties between the molded article and the mold, minimizes component transfer to the molded article, and enhances the adhesion of the molded article. The release agent of this invention comprises a wax emulsion formed by emulsifying multiple hydrocarbon waxes with a melting point difference of 25°C or more between any two types of hydrocarbon waxes.

Description

Technical Field

[0001] This invention relates to mold release agents, and more particularly to mold release agents suitable for manufacturing molded articles made of polyurethane resins and the like with excellent release and adhesion properties. Background Technology

[0002] In the molding of porous plastic foams such as polyurethane resin, release agents containing wax or silicone, or mixtures thereof, as non-volatile components are used to facilitate demolding of the molded article from the mold. Therefore, the components of the release agent are transferred from the mold to the surface of the molded article. The transferred components are chemically inactive and are in the form of paste, oil, or solid, which sometimes results in poor adhesion of the molded article. For example, in the manufacture of leather-wrapped steering wheels, insufficient adhesion sometimes occurs when bonding leather material to the molded article due to the components of the release agent transferred onto the molded article.

[0003] Examples of pretreatments to improve the adhesion of molded articles include sanding, wiping with organic solvents, and polishing. Patent Document 1 discloses an invention for bonding porous plastic foam molded articles, in which the bonding surface of the molded article is washed with a mixture of silica powder and solvent, and every 1m² of the bonding surface... 2 After attaching 1-10g of silica, use an adhesive to bond them together.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent No. 4800811 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] Even with the above pretreatment, it is sometimes impossible to remove the mold release agent. Furthermore, due to the complexity of the pretreatment, it is desirable to bond the molded parts without pretreatment.

[0009] The present invention was made in view of the above circumstances, and its object is to provide a release agent that has good release properties between the molded article and the mold, minimal transfer of components to the molded article, and good adhesion of the molded article.

[0010] Technical solutions for solving the problem

[0011] Through in-depth research, the inventors discovered that a release agent containing a wax emulsion formed by emulsifying two types of hydrocarbon waxes with a melting point difference of more than 25°C not only provides good release properties between the molded product and the mold, but also results in less transfer on the molded product and good adhesion of the molded product, thus completing the present invention.

[0012] That is, in one aspect of the present invention, the release agent comprises a wax emulsion formed by emulsifying multiple types of hydrocarbon waxes with a melting point difference of more than 25°C between any two types of hydrocarbon waxes.

[0013] Here, the difference in melting points is determined by performing DSC (Differential Scanning Calorimetry) on a mixture of two types of hydrocarbon waxes, and is obtained by comparing the two peaks of the resulting DSC curve.

[0014] Each of the two types of hydrocarbon waxes may contain one type of hydrocarbon wax, or it may be a mixture of two or more types of hydrocarbon waxes.

[0015] Multi-class hydrocarbon waxes refer to two or more types of hydrocarbon waxes.

[0016] In the above-mentioned release agents, the difference in melting point can be less than 90°C.

[0017] One embodiment of the present invention involves a release agent comprising a wax emulsion formed by emulsifying two types of hydrocarbon waxes with a melting point difference of 25°C or more, wherein the weight ratio of the hydrocarbon wax on the high melting point side to the hydrocarbon wax on the low melting point side is 50 / 50 or more and 92 / 8 or less.

[0018] Invention Effects

[0019] According to the present invention, the molded article has good demolding properties from the mold, less component transfer to the molded article, and good adhesion of the molded article. Attached Figure Description

[0020] Figure 1 The graphs show the relationship between melting point difference and demolding force, and between melting point difference and adhesive force, based on the same weight ratio of wax on the high melting point side to wax on the low melting point side in Examples 3, 4 and Comparative Example 3.

[0021] Figure 2 The graph shows the relationship between the ratio of the hydrocarbon wax on the high melting point side to the total amount of hydrocarbon wax (100% by weight) and the release force, and the relationship between the above ratio and the adhesive force, based on Examples 1, 2, 3 and Comparative Example 1 with the same melting point difference. Detailed Implementation

[0022] The embodiments of the present invention will be described in detail below.

[0023] One embodiment of the present invention involves a release agent comprising a wax emulsion formed by emulsifying multiple hydrocarbon waxes of any selection, the difference in melting point of two types of hydrocarbon waxes being greater than 25°C.

[0024] Hydrocarbon waxes can be either natural or synthetic waxes. Examples of natural waxes include animal and plant waxes, petroleum waxes, and other mineral waxes. Examples of petroleum waxes include paraffin wax, microcrystalline wax, and petroleum jelly. Examples of synthetic waxes include Fischer-Tropsch wax and polyethylene wax.

[0025] Each of the two types of hydrocarbon waxes may contain one of the aforementioned hydrocarbon waxes, or may be a mixture of two or more hydrocarbon waxes.

[0026] When the melting point difference between the two types of hydrocarbon waxes is greater than 25°C, the molded product exhibits good release properties and adhesion to the mold. This is believed to be because the release agent film strength increases with the high-melting-point hydrocarbon wax, resulting in less transfer of components onto the molded product, while the low-melting-point hydrocarbon wax ensures good release properties.

[0027] The difference in melting points between the two types of hydrocarbon waxes is preferably less than 90°C. The upper limit of the difference in melting points is preferably in the order of 80°C, 73°C, 63°C, 60°C, and 55°C. The lower limit of the difference in melting points is more preferably in the order of 30°C, 35°C, and 40°C.

[0028] The amount of hydrocarbon wax in the wax emulsion can be appropriately set according to the type and proportion of the hydrocarbon wax, the type and amount of other compounding components, etc. For example, the total amount of hydrocarbon wax relative to 100% by weight of the wax emulsion is preferably set to 1% by weight or more and 30% by weight or less. In this case, emulsion particles can be easily formed, and the molded article has good demolding properties and good adhesion to the mold. The lower limit of the total amount of hydrocarbon wax is more preferably 3% by weight. The upper limit of the total amount of hydrocarbon wax is more preferably 20% by weight, and even more preferably 15% by weight.

[0029] One embodiment of the present invention involves a release agent comprising a wax emulsion formed by emulsifying two types of hydrocarbon waxes with a melting point difference of 25°C or more, wherein the weight ratio of the hydrocarbon wax on the high melting point side to the hydrocarbon wax on the low melting point side is 50 / 50 or more and 92 / 8 or less. In this case, it is considered that the molded article exhibits good release properties from the mold and good adhesion to the molded article. With this weight ratio, the release agent film strength increases due to the high melting point hydrocarbon wax, resulting in less transfer on the molded article, while the low melting point hydrocarbon wax ensures good release properties. The lower limit of the above weight ratio is more preferably 53 / 47, and further preferably 60 / 40. The upper limit of the above weight ratio is more preferably 88 / 12, and further preferably 82 / 18.

[0030] The wax emulsion contains water. The water used can be any of the following: tap water, industrial water, ion-exchanged water, distilled water, etc., and can be either hard or soft water. The amount of water in the wax emulsion, relative to 100% by weight, can be set to 70% by weight or more and 95% by weight or less. The lower limit of the water content is preferably 80% by weight, and the upper limit is preferably 90% by weight.

[0031] Wax emulsions are obtained by emulsifying hydrocarbon waxes using an emulsifier. Well-known surfactants can be appropriately used as emulsifiers.

[0032] As a surfactant, any of the following can be used: anionic surfactant, cationic surfactant, amphoteric surfactant, and nonionic surfactant. A single surfactant can be used, or two or more can be used in combination.

[0033] Examples of anionic surfactants include fatty acid salts and alkyl sulfonates. Examples of cationic surfactants include alkylamine salts and alkylammonium salts. Examples of amphoteric surfactants include fatty acid-type amphoteric surfactants and sulfonic acid-type amphoteric surfactants. Furthermore, examples of nonionic surfactants include glycerol fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxysorbitol fatty acid esters, and polyoxyalkylene alkyl ethers.

[0034] The amount of emulsifier can be appropriately set according to the type of emulsifier, the types and amounts of other compounding components, etc. For example, the amount of emulsifier relative to 100% by weight of the wax emulsion is preferably set to be greater than 0% by weight and less than 9.0% by weight. In this case, the target emulsion particles can be easily formed, the stability of the wax emulsion is improved, and the molded product has excellent demolding properties. The lower limit of the amount of emulsifier is more preferably 0.1% by weight, and even more preferably 0.5% by weight. The upper limit of the total amount of emulsifier is preferably 7.0% by weight, 5.0% by weight, and 3.0% by weight, in that order.

[0035] Wax emulsification can be carried out using conventional methods, but considering the stability during emulsification, phase inversion emulsification is the preferred method.

[0036] When preparing wax emulsions, other additives such as emulsifying agents and pH adjusters can be used.

[0037] Examples of emulsifying aids include higher alcohols such as cetyl alcohol and lauryl alcohol, higher fatty acids such as lauric acid, palmitic acid, and stearic acid, oxidized waxes, chlorinated paraffins, and liquid paraffins. The amount of emulsifying aid can be appropriately set according to the type of emulsifying aid, the type of other compounding components, and their amounts. For example, the amount of emulsifying aid relative to 100% by weight of the wax emulsion is preferably set to 0% by weight or more and 9.0% by weight or less. In this case, the target emulsion particles can be easily formed, the stability of the wax emulsion is improved, and the molded article exhibits excellent demolding properties. The lower limit of the amount of emulsifying aid is more preferably 0.1% by weight, and even more preferably 0.5% by weight. The upper limit of the amount of emulsifying aid is more preferably 7.0% by weight, and even more preferably 5.0% by weight.

[0038] Examples of pH adjusters include inorganic bases such as sodium hydroxide, potassium hydroxide, and ammonia, and organic bases such as triethylamine. The amount of pH adjuster can be appropriately set depending on the type of pH adjuster, the types and amounts of other components, etc. For example, the amount of pH adjuster relative to 100% by weight of the wax emulsion is preferably set to 0% by weight or more and 3% by weight or less. In this case, the pH of the wax emulsion can be set to weakly alkaline, which can prevent mold corrosion and inhibit wax emulsion spoilage. The lower limit of the pH adjuster is more preferably 0.1% by weight, and even more preferably 0.2% by weight. The upper limit of the pH adjuster is more preferably 1% by weight.

[0039] The wax emulsion of this embodiment can be used directly as a release agent. Alternatively, the wax emulsion of this embodiment can be used as a stock solution and further diluted with a diluent such as water to prepare a release agent. The dilution ratio can be appropriately set according to the amount of hydrocarbon wax in the wax emulsion.

[0040] When the wax emulsion is diluted, the amount of wax emulsion incorporated relative to 100% by weight of the release agent is preferably 1% by weight or more and 40% by weight or less. The lower limit of the amount incorporated is more preferably 2% by weight, and even more preferably 5% by weight. The upper limit of the above-mentioned amount incorporated is more preferably 30% by weight, and even more preferably 20% by weight. The solid component relative to 100% by weight of the release agent is preferably 0.5% by weight or more and 2% by weight or less.

[0041] In the case of preparing a release agent by diluting a wax emulsion, the wax emulsion and water are added in any ratio to a container equipped with a stirring device, and stirred until a homogeneous solution is formed, thereby obtaining a water-based release agent. During preparation, the emulsion-formed substance is mixed with water; no special heating is required.

[0042] As a method for applying the release agent of this embodiment to the mold, there are methods such as spraying or brushing. The amount of non-volatile components of the release agent adhering to the mold is [amount missing] per 1m [unit missing].2 The amount is 0.5g or more and 20g or less, preferably 3g or more and 10g or less. By applying the above amount to the mold, sufficient demolding properties can be obtained, mold contamination is reduced, and it is also economically advantageous.

[0043] When using the mold release agent of this embodiment, the mold temperature during molding is 40°C or higher and 80°C or lower, preferably 60°C or higher and 80°C or lower. If the mold temperature is too low, the evaporation rate of water, which is a solvent, will be slower, which is not preferable from the viewpoint of work efficiency.

[0044] In addition, the release agent of this embodiment may be combined with other release agents such as alcohols such as ethanol, fluorine components, silicone components, rust inhibitors, and corrosion inhibitors as needed.

[0045] Synthetic resins used as fillers in molds include polyurethane resin, polyethylene resin, polypropylene resin, polyester resin, epoxy resin, phenolic resin, etc., with polyurethane resin being the preferred choice.

[0046] Materials that can be used to bond to molded products include synthetic resins such as polyacrylic acid resin, polyamide resin, polyolefin resin, and polyvinyl chloride resin, as well as natural leather such as cowhide, synthetic leather, cloth, metal, and ceramics.

[0047] As an adhesive, various conventionally known adhesives can be used. Examples include rubber-based adhesives such as styrene-butadiene rubber and neoprene rubber, thermosetting adhesives such as epoxy resin-based adhesives and polyurethane-based adhesives. There are no particular limitations on the application method of these adhesives; they can be applied using a scraper, a brush, or by spraying. From a workability point of view, spraying is preferred among these application methods.

[0048] Example

[0049] The following describes specific embodiments of the present invention, but the present invention is not limited to these embodiments.

[0050] 1. Preparation of release agent [Example 1]

[0051] Wax 1, Wax 5, emulsifying aid, emulsifier, and pH adjuster, in the proportions (in parts by weight) shown in Table 1 below, were heated and melted. Water (hot water) was slowly added, and a wax emulsion was obtained through phase inversion emulsification. The wax emulsion was diluted with water to a ratio of 9:1 to obtain the release agent of Example 1. Wax 5 is a mixture of two hydrocarbon waxes. The melting points of Wax 1 and Wax 5 in Table 1 were determined by DSC using a differential scanning calorimeter (DSC) with the trade name "EXSTA6000DSC6200" (manufactured by Seiko Instruments Co., Ltd.). The difference between the two peaks was taken as the melting point difference between Wax 1 and Wax 5. The melting points and melting point differences were also determined in the same way in other examples and comparative examples.

[0052] Table 1

[0053]

[0054] [Examples 2 and 3]

[0055] The mixing ratio of wax 1 and wax 5 was changed as shown in Table 1 above. Otherwise, the release agents of Examples 2 and 3 were prepared in the same manner as in Example 1.

[0056] [Examples 4 and 5]

[0057] According to the mixing ratios in Table 1 above, wax 3 and wax 5, wax 1 and wax 6 were mixed. Except for this, the release agents of Examples 4 and 5 were prepared in the same manner as in Example 1.

[0058] [Comparative Examples 1-7]

[0059] The wax was formulated according to the formulation ratios in Table 2 below. Otherwise, the release agents of Comparative Examples 1 to 7 were prepared in the same manner as in Example 1.

[0060] Table 2

[0061]

[0062] 2. Performance Evaluation

[0063] Manufacture the molded article as described below, and evaluate the demolding properties of the molded article and the adhesion properties of the molded article to the mold.

[0064] [Manufacturing of molded products]

[0065] On the inner wall surface of the test mold heated to 65±3℃, 13g of the release agent of Examples 1-5 and Comparative Examples 1-7 was uniformly sprayed onto each mold using a spray gun.

[0066] Polyurethane resin is injected into a mold and cured to obtain the molded product.

[0067] [Demolding performance evaluation]

[0068] After the polyurethane resin has cured, the load required to demold the molded article from the mold is measured using a push-pull force gauge. This load is recorded as the demolding force. The evaluation of the demolding force is shown in the lower part of Tables 1 and 2 above. The evaluation is as follows.

[0069] A: Below 80N

[0070] B: 80N or higher but less than 100N

[0071] C: 100N or higher

[0072] [Adhesion Evaluation]

[0073] Adhesive was applied to both the molded article and the leather with a brush. The leather was then bonded to the molded article. After standing in a constant temperature bath at 23°C for 24 hours, the leather was peeled off the molded article by a 180° peel test. The load required for peeling was measured using a push-pull force gauge. This load was recorded as the adhesive force. The evaluation of the adhesive force is shown in the lower part of Tables 1 and 2 above. The evaluation content is as follows.

[0074] A: 15N or higher

[0075] B: 10N or higher but less than 15N

[0076] C: Below 10N

[0077] Figure 1 The graphs showing the relationship between melting point difference and demolding force, and melting point difference and adhesive force are derived from Examples 3, 4, and Comparative Example 3, where the weight ratio of wax on the high melting point side to wax on the low melting point side is the same. Figure 1 The horizontal axis represents the melting point difference (°C), the vertical axis on the left represents the demolding force (N), and the vertical axis on the right represents the adhesive force (N). Figure 1 In the graph, the solid line represents the relationship between melting point difference and demolding force, while the dashed line represents the relationship between melting point difference and adhesive force.

[0078] According to Tables 1 and 2, and Figure 1 It can be seen that in the example where the melting point difference between the two types of hydrocarbon wax is more than 25°C, the molded article has good demolding properties and good adhesion to the mold compared with the comparative example.

[0079] The upper limit of the melting point difference is preferably 90℃, 80℃, 73℃, 63℃, 60℃, and 55℃ in that order. The lower limit of the melting point difference is more preferably 30℃, 35℃, and 40℃ in that order.

[0080] Figure 2 Based on Examples 1, 2, 3, and Comparative Example 1 with the same melting point difference, the graph shows the relationship between the ratio of the hydrocarbon wax on the high melting point side to the total amount of hydrocarbon wax (100% by weight) and the release force, and the relationship between the above ratio and the adhesive force. Figure 2 The horizontal axis represents the ratio (%), the vertical axis on the left represents the demolding force (N), and the vertical axis on the right represents the adhesive force (N). Figure 2 In the graph, the solid line shows the relationship between the ratio and the release force, and the dashed line shows the relationship between the ratio and the adhesive force.

[0081] According to Tables 1 and 2, and Figure 2 It can be seen that in the examples where the ratio of the high-melting-point hydrocarbon wax to the low-melting-point hydrocarbon wax is 50% by weight or more and 92% by weight or less, that is, when the weight ratio of the high-melting-point hydrocarbon wax to the low-melting-point hydrocarbon wax is 50 / 50 or more and 92 / 8 or less, the release properties and adhesion are better compared to the comparative examples. The lower limit of the above weight ratio is more preferably 53 / 47, and even more preferably 60 / 40. The upper limit of the above weight ratio is more preferably 88 / 12, and even more preferably 82 / 18.

[0082] Based on the above, the release agent of the present invention is confirmed to have good release properties between the molded article and the mold, and also good adhesion properties between the molded article and the mold.

[0083] The above embodiments describe the preparation of wax emulsions by combining two types of hydrocarbon waxes, but are not limited to this. For example, wax emulsions can also be prepared by combining three types of hydrocarbon waxes.

Claims

1. A release agent comprising a wax emulsion formed by emulsifying multiple types of hydrocarbon waxes, wherein the melting point difference between any two types of hydrocarbon waxes selected from the multiple types of hydrocarbon waxes is greater than 30°C. The weight ratio of the high-melting-point hydrocarbon wax to the low-melting-point hydrocarbon wax in the two types of hydrocarbon waxes is greater than 53 / 47 and less than 82 / 18. The water content is between 70% and 95% by weight relative to 100% of the wax emulsion.

2. The release agent according to claim 1, wherein, The difference in melting points is below 90°C.

3. The release agent according to claim 1, wherein, The total amount of the various hydrocarbon waxes is more than 1% and less than 15% by weight relative to 100% by weight of the wax emulsion.

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