Methods for producing molding compound

Abstract

A method for producing a molding compound, the molding compound comprising at least an adhesive and a plasticizer, the adhesive and the plasticizer being in the form of a plastisol, the plastisol being substantially composed of PVC and the plasticizer, characterized in that the production method is carried out in the following steps: in a first step, PVC powder and a certain amount of plasticizer are subjected to a mixing process with any other supplements and / or additives, and the mixing process is carried out at a mixing temperature of about 55 to 70°C.

Description

[0001] This invention relates to a method for producing molding compound.

[0002] Plastic molding compounds used to shape objects and their production methods are known in principle. Objects can be designed manually or mechanically for industrial applications.

[0003] Molding compounds are also understood to refer to so-called clay, or, in the case of polymer-containing compounds, to so-called polymer clay. These molding compounds have an extremely wide range of applications in everyday life today.

[0004] Molding compounding materials of the form of molding compounding material selected from existing technologies are used as examples.

[0005] DE 25 15 757 C3 discloses a plastic compound that can be manually deformed and hardened by heat.

[0006] These compounding materials are basically composed of polyvinyl chloride (PVC), fillers, and phthalate-containing plasticizers.

[0007] DE 10 2005 059 143 A1 also discloses molding compounds that do not use plasticizers containing phthalates.

[0008] The disadvantage of such formulations based on the selected prior art is that they are not resistant to aging, and, for example, even in unopened packaging, the blocks of shaping formulations show an increase in hardness after long-term storage. Therefore, shaping formulations are difficult for users to knead.

[0009] This issue also represents the ideal situation of aging, as long storage times can even cause blocks of molding compound and molding materials to become unusable in most cases because they can no longer be manually kneaded.

[0010] This is due to the fact that the plasticizers in the compound have already shown interaction at room temperature. This is known as the aging process of PVC-containing molding compounds in an uncured state.

[0011] For the molding compound according to the mentioned prior art, the powdered raw material is mixed with the plasticizer at a temperature between 20°C and 30°C. This achieves a plasticizer absorption of 25-30% by weight. Individual PVC agglomerates disintegrate over a certain period (e.g., during long storage), which in turn creates a need for the plasticizer because the surface area of ​​the PVC particles has increased.

[0012] In this situation, the plasticizer initially stored in the intermediate spaces between PVC particles (which primarily determines the soft kneading / kneading behavior of the molding compound) is no longer present. Instead, the plasticizer accumulates on the newly formed surfaces of the disintegrating aggregates. Due to this phenomenon, the hardness of the uncured molding compound increases over time.

[0013] Therefore, the object of the present invention is to create a method for producing molding compounds that does not have the aforementioned disadvantages, particularly minimizing the aging process during storage of PVC-containing molding compounds in an uncured state, and thereby ensuring greater storage stability, which represents a particular consumer advantage.

[0014] This objective is achieved using the features included in claim 1. Advantageous improvements and developments to the method according to the invention are included in the additional claims.

[0015] It has been surprisingly shown that this objective can be achieved using a method according to the invention for producing molding compound by subjecting an adhesive (PVC powder) and a certain amount of plasticizer to a mixing process with any other supplements and / or additives, said mixing process being carried out at a mixing temperature of 55 to 70°C, preferably 58 to 65°C.

[0016] In the method according to the invention, the molding compound comprises the following components:

[0017] 20-68% by weight of adhesives

[0018] 32-60% by weight plasticizer

[0019] 0-40% by weight of filler; and

[0020] 0-20% by weight of other additives.

[0021] In this method, a preferred embodiment of the molding compound includes:

[0022] 40-68% by weight of adhesives

[0023] 35-55% by weight plasticizer

[0024] 0-40% by weight of filler, and

[0025] 0-20% by weight of other additives.

[0026] Particularly preferred embodiments of the molding compound include:

[0027] 45-63% by weight adhesive,

[0028] 38-52% by weight plasticizer

[0029] 0-17% by weight of filler, and

[0030] 0-15% by weight of other additives.

[0031] It has been surprisingly shown that by supplying / introducing higher amounts of plasticizer into PVC systems for molding compounding, the hardness of the compound is reduced over time, thereby significantly improving storage stability.

[0032] Furthermore, it has been surprisingly found that the more plasticizer added to PVC powder, the higher the flexibility of the compound after the curing process. The higher plasticizer content significantly improves the flexibility of the cured compound.

[0033] It has also been surprisingly shown that the method according to the invention can also be used to obtain greater transparency after the hardening process.

[0034] The molding compound produced using the method according to the invention comprises: a binder in the form of a plastisol, which is essentially composed of PVC and a plasticizer; and optionally other supplements and / or additives. For example, the molding compound may contain at least one filler as an additional supplement and / or additive. The molding compound according to the invention exhibits the following properties when the plasticizer content in the mixture is adjusted such that the plasticizer attaches itself to the surface of the PVC particles and is stored in the intermediate spaces between the solid particles, thereby forming a "kneadable tolerance (Widerstand)". If the plasticizer content is too low (i.e., the plasticizer only accumulates on the surface of the solid particles and is not also present in the intermediate spaces), the compound is too stiff or very difficult to mold, regardless of whether the molding compound is processed manually or by machine.

[0035] On the other hand, if the surface of the solid particles and the intermediate space between the solid particles are completely covered or even oversaturated by plasticizer, the resulting molding material will be too fluid and therefore will no longer be able to be molded in a controllable manner.

[0036] To illustrate the principle of the method according to the invention, a description will be made using modeling materials, so as to clearly demonstrate that the invention is superior to the prior art in terms of modeling materials.

[0037] Heat must be provided to transform the currently molded, designed / shaped subject and object into a permanent solid. For example, in the case of shaped compounds, this is known as bake curing. The plasticizer, or plasticizer content, determines the curing process, allowing the compound to harden due to its interaction with PVC.

[0038] However, it has been shown that plasticizers retain an affinity for PVC particles or solid PVC particles even when stored at room temperature, ensuring the decomposition of PVC particles, which are partially composed of agglomerates, thereby creating new surfaces / surface areas. Plasticizers stored in the intermediate space migrate through these newly generated surfaces. Consequently, the hardness of the molding compound increases because moldability is reduced due to the lack of liquid plasticizer components in the intermediate space.

[0039] A particular advantage is that by mixing with a larger amount of plasticizer at a higher temperature, the agglomerates can be disintegrated (= aging process) earlier during the production process using the method according to the invention.

[0040] This ultimately improves storage stability or the hardness of the uncured compound as it increases over time, for example, by adding plasticizers in a targeted manner after the “aging process during manufacturing” has already begun.

[0041] Another advantage arising from the increased proportion / content of plasticizers in molding compounds is the improved ability to gel in the system during the curing process, resulting in greater elasticity after curing. It has been surprisingly shown that by mixing at higher temperatures and with appropriate plasticizer contents, and by reducing the use of fillers and / or additives, the transparency after bake curing can be significantly improved.

[0042] The adhesive used (which is essentially in the form of PVC) and the added plasticizer form a plastisol. Furthermore, PVC can exist in the form of emulsion PVC with or without emulsifiers, suspension PVC, microsphere suspension PVC, or mixtures of various PVC types.

[0043] Phthalate-free plasticizers and / or phthalate-containing plasticizers can be used as plasticizers.

[0044] The total plasticizer content is between 32 and 60% by weight, between 35 and 55% by weight in a preferred embodiment, and between 38 and 53% by weight in a particularly preferred embodiment.

[0045] Phthalate-free plasticizers are based on citric acid, adipic acid and / or benzoates.

[0046] For example, phthalate-free plasticizers are tributyl acetylacetonate, tri(2-ethylhexyl) acetylacetonate, trioctyl citrate, tridecyl citrate, tributyl citrate, trihexyl citrate, triethyl citrate, dioctyl adipate, diisodecyl adipate, diisononyl adipate, bis(2-ethylhexyl) adipate, diisononyl 1,2-cyclohexanedicarboxylate, glyceryl monoacetate, benzoates, or mixtures of at least two of the aforementioned substances. Plasticizers may also belong to the group consisting of benzoates or benzoic acid esters. 2,2,4-triethyl-1,3-pentanediyl dibenzoate and its derivatives, triethylene glycol dibenzoate, diethylene glycol dibenzoate, diethylene glycol monobenzoate, and / or propylene glycol dibenzoate are mentioned as examples. Any mixture of all the foregoing plasticizers is possible.

[0047] Examples of plasticizers containing phthalates are di-2-ethylhexyl phthalate, ditridecyl phthalate, and dibutyl phthalate.

[0048] Any mixture of phthalate-containing plasticizers is possible. A mixture of plasticizers consisting of phthalate-free and phthalate-containing plasticizers may also be used.

[0049] A preferred embodiment of the method of the present invention is to produce molding compound that does not contain phthalate-containing plasticizers.

[0050] Stabilizers improve the stability of PVC, and in addition, they prevent the release of hydrogen chloride. In particular, inorganic and organic salts of metallic calcium, zinc, tin, magnesium, sodium, and potassium are used for this purpose, such as calcium stearate, sodium stearate, potassium stearate, zinc stearate, magnesium stearate, tin stearate, and / or mixtures of said metallic salts.

[0051] Inorganic and organic fillers with particle sizes <250μm, preferably less than 100μm, are generally used as fillers, such as kaolin, chalk, silica, talc, aluminum hydroxide, and / or powdered clay.

[0052] For example, metallic glitter, glitter powder and glitter flakes, or mixtures of said substances can be present as additional fillers to achieve special optical effects.

[0053] So-called lightweight fillers can also be used as fillers, or can be blended with other fillers mentioned above. Examples of lightweight fillers are hollow spheres, particularly hollow glass microspheres, such as those from 3M or Lehmann & Voss. The desired density can be set according to the content of the lightweight filler, which is advantageously in the range of 0.3 to 1.1 g / ml. The size of commercially available lightweight fillers can also be freely selected, preferably in the range of 10 to 400 μm.

[0054] In addition, polymer-based fillers may also be used. PAMA, PMMA, and / or polyethylene are specified as examples of this group.

[0055] Pigments can exist in the following forms: pure colorants, powder pigments, preferably azo-free coloring pigments, effect pigments, and / or azo-free lake dyes. A wide range of possible coloring pigments include Pigment Yellow 14 (CI21095), Pigment Red 254 (CI56110), Pigment Orange 34 (CI21110), Pigment Red 122 (CI73915), Pigment Green 7 (CI74260), Pigment White 6 (CI77891), Pigment Black 7 (CI77266), Pigment Red 101 (CI77491), Pigment Violet 23 (CI51319), Pigment Blue 29 (CI77007), Pigment Yellow 185 (CI56290), Pigment Yellow 1 (CI11680), Pigment Red 48:2 (CI15865:2), Pigment Red 53:1 (CI15585:1), Pigment Orange 34 (CI21115), Pigment Yellow 83 (CI21108), and Pigment Blue 15 (CI74160).

[0056] The addition of these colorants gives the molding compound a vibrant appearance.

[0057] Pearl pigments, mica-iron metallic pigments, polyester glitter pigments, and luminescent pigments can be specified as additional colorants.

[0058] This shows that molding compound materials with different colors can be mixed, blended or kneaded together as needed to achieve a marble texture effect.

[0059] The invention will be described in more detail using framework examples based on molding compound and some formulation examples.

[0060] Example 1 of a framework for molding compound

[0061] 20-68% by weight adhesives

[0062] 32-60% by weight plasticizer

[0063] 0-40% by weight of filler

[0064] 0-20% by weight of other additives

[0065] Frame Example 2 - Preferred Composition

[0066] 40-68% by weight adhesives

[0067] 35-55% by weight plasticizer

[0068] 0-20% by weight of filler

[0069] 0-20% by weight of other additives

[0070] Frame Example 3 - Particularly Preferred Composition

[0071] 45-63% by weight adhesive

[0072] 38-53% by weight plasticizer

[0073] 0-17% by weight of filler

[0074] 0-15% by weight of other additives

[0075] Stabilizers, co-stabilizers, colorants and / or fillers are examples of other additives that may be used.

[0076] Formulation Example 1 - Yellow Molding Compound

[0077] 51% by weight of E-PVC and S-PVC

[0078] 42% by weight of ATBC-based plasticizer

[0079] 6% by weight of stabilizer

[0080] 0.5% by weight of filler

[0081] 0.5% by weight of Pigment Yellow 83

[0082] Formulation Example 2 - Transparent Molding Compound After Hardening

[0083] 48% by weight of E-PVC and S-PVC

[0084] 52% by weight of ATBC-based plasticizer

[0085] Prior art - comparative formulation according to DE 10 2005 059 143

[0086] 59% by weight of PVC

[0087] 24% by weight of citric acid-based plasticizer

[0088] 1% by weight of stabilizer

[0089] 7% by weight of co-stabilizer

[0090] 4% by weight of filler

[0091] 1% by weight of Pigment Red 254

[0092] The preferred phthalate-free plasticizers used are based on citric acid and / or adipic acid.

[0093] The desired consistency of the compound can be easily adjusted by changing the binder content and / or plasticizer content.

[0094] The invention will be described in more detail using the following table using the molding compound.

[0095] Table 1: Hardness of uncured compound at 40℃ as a function of time

[0096]

[0097] It has been shown that, compared with the prior art, the compound according to this application, which has not yet been hardened in an oven, has a significantly lower hardness increase when stored at 40°C over time (30 days or 90 days), as shown in Table 1.

[0098] Table 2: Flexibility of Hardened Molding Compounds

[0099]

[0100] These high fracture strengths can be determined and confirmed using a texture analyzer. Circular fracture bars with a length of 10 cm and a diameter of 1 cm are produced as test samples.

[0101] The molding compound produced according to the present invention is used in automotive construction, household articles, medical devices, toys and the food industry, as well as accessories for the above uses.

[0102] Articles and objects formed from molding compounds produced according to the present invention are hardened by heat after molding.

[0103] A method for producing molding compound is performed by subjecting PVC powder and a certain amount of plasticizer with optional supplements and / or additives to a mixing process at a mixing temperature between 55 and 70°C. The molding compound consists of at least a binder and a plasticizer in the form of a plastisol, which is substantially composed of PVC and the plasticizer.

Claims

1. A method for producing a molding compound, said molding compound comprising at least a binder and a plasticizer, said binder and said plasticizer being in the form of a plastisol, said plastisol being substantially composed of PVC and the plasticizer, characterized in that, The method is carried out by subjecting PVC powder and a certain amount of plasticizer to a mixing process with any other supplements and / or additives, and the mixing process is carried out at a mixing temperature of 55 to 70°C, wherein the plasticizer is formed as a phthalate-free plasticizer based on citric acid, and wherein the content of the plasticizer is between 32 and 60% by weight.

2. The method according to claim 1, characterized in that, The plasticizer content is between 35% and 55% by weight.

3. The method according to claim 2, characterized in that, The plasticizer content is between 38% and 53% by weight.

4. The method according to claim 1, characterized in that, The plasticizer is tributyl acetylacetonate, tri(2-ethylhexyl) acetylacetonate, trioctyl citrate, tridecyl citrate, tributyl citrate, trihexyl citrate, triethyl citrate, or a mixture of at least two of the above substances.

5. The method according to any one of the preceding claims, characterized in that, The molding compound consists of at least the following:

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