Manufacturing method of molding compound

Abstract

1. A method for producing a molding compound consisting of at least a binder and a plasticizer, wherein the binder and the plasticizer are formed as a plastisol, the plastisol essentially consisting of PVC and the plasticizer, characterized in that the production method comprises the steps of: in a first step, subjecting PVC powder and a certain amount of plasticizer, optionally together with other additives and / or additives, to a mixing process, the mixing process being carried out at a mixing temperature of about 55-70°C.

Description

[Technical field]

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

[0002] Plastic moulding compounds and methods for their production are known in principle for shaping articles, where the shaping of the articles can take place manually or, in industrial applications, by machine.

[0003] Moulding compounds are also understood to mean so-called clays or, in the case of polymer-containing compounds, so-called polymer clays. Such moulding compounds are used in a very wide range of applications in everyday life today.

[0004] For example, the prior art mentions moulding compounds in the form of moulding compounds. For example, from DE 2515757 C1 compounds are known which are plastic, can be deformed by hand and can be hardened by heating. Such compounds essentially consist of polyvinyl chloride (PVC), fillers and phthalate-containing plasticisers.

[0005] Furthermore, from DE 10 2005 059 143 A1, moulding compounds are known which are free of phthalate-containing plasticisers.

[0006] A disadvantage of such compounds according to the selected prior art is that they are not resistant to aging and that, for example, blocks of molding compound show an increase in hardness on long-term storage, even in unopened packaging. This makes it difficult for the user to knead the molding compound. This problem is still an ideal case for aging, since long-term storage may even make it impossible to knead by hand and render the molding block, and even the molding compound in general, unusable. This may be due to the fact that the plasticizers in the compound already show an interaction at room temperature. This is referred to as the aging process of PVC-containing molding compounds in the uncured state. In the case of the molding compounds according to the aforementioned prior art, the powdered raw materials are mixed with the plasticizer at a temperature of 20-30 ° C. In this case, a plasticizer absorption of 25-30 wt. % is achieved. Over time, for example, the disintegration of the individual PVC agglomerates on long-term storage increases the surface area of ​​the PVC particles, which in turn requires a plasticizer. The plasticizers that initially accumulated in the gaps between the PVC particles, which are largely responsible for the soft kneading / kneading behavior of the molding compound, are no longer present in this case. Instead, the plasticizers accumulate on the newly generated surfaces of the disintegrated agglomerates. As a result, this phenomenon causes the hardness of the uncured molding compound to increase over time.

[0007] The object of the present invention is therefore to create a process for the production of molding compounds which does not have the disadvantages mentioned at the outset and which also minimizes the aging processes during storage of PVC-containing molding compounds, in particular in the uncured state, and thus ensures a higher storage stability, which represents a particular consumer benefit.

[0008] This problem is solved by the features contained in claim 1. Advantageous embodiments and developments of the method according to the invention are contained in the further claims.

[0009] Surprisingly, it has been found that this problem can be solved by using the method for producing a moulding compound according to the invention, by subjecting the binder (PVC powder) and an amount of plasticizer, optionally together with other additives and / or additives, to a mixing step, which mixing step is carried out at a mixing temperature between 55 and 70°C, preferably between 58 and 65°C.

[0010] The molding compound in the process according to the invention comprises as components: 20~68% by weight Binder 32-60% by weight plasticizer 0-40% by weight filler, and 0~20% by weight other additives Includes.

[0011] A preferred embodiment of the molding compound in this method is 40~68% by weight binder 35-55% by weight plasticizer 0-40% by weight filler, and 0~20% by weight other additives Includes.

[0012] A particularly preferred embodiment of the molding compound is 45~63% by weight binder 38-52% by weight plasticizer 0-17% by weight filler 0~15% by weight other additives Includes.

[0013] Surprisingly, it has been found that by adding / incorporating a larger amount of plasticizer into the PVC system of the molding compound, the increase in hardness of the compound over time is reduced and thus the storage stability is significantly improved.

[0014] Even more surprisingly, it has been found that the more plasticizer is added to the PVC powder, the more flexible the compound obtained after the curing process. This high plasticizer content significantly increases the flexibility of the cured compound.

[0015] It has also surprisingly been found that by the method according to the invention a higher transparency can also be achieved after the curing process.

[0016] The molding compound produced by the method according to the invention consists of a binder, which is present as a plastisol, which essentially consists of PVC, a plasticizer and optionally other additional substances and / or additives. The molding compound may contain, as other additional substances and / or additives, for example at least one filler. The molding compound according to the invention is produced when the content of plasticizer in the mixture is adjusted so that, on the one hand, the plasticizer accumulates on the surface of the PVC particles and, on the other hand, accumulates in the gaps between the solid particles, forming a "kneadable resistance". If the content of plasticizer is too low, i.e., if the plasticizer accumulates only on the surface of the solid particles and is not additionally present in the gaps, the compound will be too hard or very difficult to mold, regardless of whether the molding compound is processed by hand or machine. On the other hand, if the surfaces of the solid particles and the spaces between the solid particles are completely covered with plasticizer, or even if the plasticizer is supersaturated, the resulting molding compound will be too fluid and can no longer be molded in a controlled manner.

[0017] To illustrate the inventive principle of the method, a molding compound has been used to clearly explain the invention in comparison with the prior art which refers to a molding compound.

[0018] To transfer molded / modeled articles and objects into a permanently solid state, it is necessary to supply heat, which in the case of molding compounds, for example, is called oven curing. The curing process is then carried out by plasticizers or plasticizer fractions, which interact with the PVC to harden the compound.

[0019] However, it has been found that plasticizers already show a certain affinity for PVC particles or PVC solid particles when stored at room temperature, disintegrating the PVC particles, some of which consist of agglomerates, and thus generating new surfaces / surface areas. The plasticizer that has accumulated in the interstices migrates through and to this newly generated surface. As a result, the hardness of the molding compound increases, since there are no liquid plasticizer components in the interstices and the moldability decreases.

[0020] A particular advantage is that the method according to the invention allows the disintegration of the agglomerates (=aging process) to be brought forward into the production process by mixing at higher temperatures and with higher amounts of plasticizer. This results in an improved storage stability or hardness increase over time of the uncured compound, for example by targeted addition of further plasticizer after the start of the "aging process during the production process". As a further advantage, it has been found that an increase in the proportion / content of plasticizer in the molding compound improves the ability to gel in the system during the curing process and thus leads to greater elasticity after curing. Surprisingly, it has been found that by mixing at higher temperatures and the associated plasticizer content, and by reducing the use of fillers and / or additives, the transparency after oven curing can be significantly increased.

[0021] The binder used is essentially present as PVC, which together with the added plasticizer forms a plastisol, where the PVC can be present in particular as emulsifier- or emulsifier-free emulsion PVC, suspension PVC and microbead suspension PVC or a mixture of the individual PVC types.

[0022] As plasticizers, phthalate-free and / or phthalate-containing plasticizers can be used. The total content of plasticizers is 32-60% by weight, in a preferred embodiment 35-55% by weight, in a particularly preferred embodiment 38-53% by weight.

[0023] The phthalate-free plasticizers are based on citric acid, adipic acid and / or benzoic acid esters. The phthalate-free plasticizers are, for example, acetyl tributyl citrate, acetyl tri(2-ethylhexyl) citrate, trioctyl citrate, tridecyl citrate, tributyl citrate, trihexyl citrate, triethyl citrate, dioctyl adipate, diisodecyl adipate, diisononyl adipate, bis(2-ethylhexyl) adipate, diisononyl 1,2-cyclohexanedicarboxylic acid ester, acetate esters of monoglycerides, benzoates or mixtures of at least two of the above substances. The plasticizers can also belong to the group of benzoates or benzoic acid esters. Examples include 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. Any mixture of all the aforementioned plasticizers is possible.

[0024] Phthalate-containing plasticizers include, by way of example, di-2-ethylhexyl phthalate, ditridecyl phthalate and dibutyl phthalate. Any mixture of phthalate-containing plasticizers is possible. It is also possible to use a mixture of plasticizers consisting of phthalate-free and phthalate-containing plasticizers.

[0025] A preferred embodiment of the process according to the invention is the production of molding compounds which are free of phthalate-containing plasticizers.

[0026] The stabilizers improve the stability of the PVC, i.e. in particular prevent the release of hydrogen chloride. For this purpose, in particular inorganic and organic salts of the metals calcium, zinc, tin, magnesium, sodium and potassium are used, such as calcium stearate, sodium stearate, potassium stearate, zinc stearate, magnesium stearate, tin stearate and / or mixtures of metal salts.

[0027] As fillers, inorganic and organic fillers with a particle size of less than 250 μm, preferably less than 100 μm, such as kaolin, chalk, silica, talc, aluminum hydroxide and / or powdered clay are essentially used. As further fillers, metal glitters, glitter powders and glitter flakes or mixtures of said substances may be present, whereby, for example, special optical effects are achieved. As fillers, so-called lightweight fillers may be used and may also be blended with the other fillers mentioned. Examples of lightweight fillers are hollow spheres, in particular hollow glass microspheres, for example from the company 3M or Lehmann & Voss. Depending on the content of the lightweight filler, the desired density can be set, which is advantageously in the range of 0.3 to 1.1 g / ml. The size of the commercially available lightweight fillers can also be freely selected, which preferably ranges from 10 to 400 μm. In addition, it is also possible to use polymer-based fillers. Examples of this group include PAMA, PMMA and / or polyethylene.

[0028] As colorants, pigments can be present in pure form, as powder pigments, preferably as azo-free color pigments, effect pigments and / or azo-free coated dyes. A large selection of possible color pigments includes Pigment Yellow 14 (CI 21095), Pigment Red 254 (CI 56110), Pigment Orange 34 (CI 21110), Pigment Red 122 (CI 73915), Pigment Green 7 (CI 74260), Pigment White 6 (CI 77891), Pigment Black 7 (CI 77266), Pigment Red 101 (CI 77491), Pigment Violet 101 (CI 77491), Pigment Yellow ... Pigment 23 (CI 51319), Pigment Blue 29 (CI 77007), Pigment Yellow 185 (CI 56290), Pigment Yellow 1 (CI 11680), Pigment Red 48:2 (CI 15865:2), Pigment Red 53:1 (CI 15585:1), Pigment Orange 34 (CI 21115), Pigment Yellow 83 (CI 21108) and Pigment Blue 15 (CI 74160). The addition of these colorants gives the molding compound a vibrant appearance. Further colorants are presented as pearlescent pigments, mica and iron metallic luster pigments, polyester luminescent pigments and luminescent pigments.

[0029] It has now been found that the variously colored molding compounds can furthermore optionally be blended, mixed or kneaded with one another in order to obtain a marbling effect.

[0030] The present invention will now be described in more detail with reference to the molding compounds using construction examples and some formulation examples.

[0031] Molding compound composition example 1 20~68% by weight Binder 32-60% by weight plasticizer 0-40% by weight filler 0~20% by weight other additives

[0032] Configuration Example 2: Preferred composition 40~68% by weight binder 35-55% by weight plasticizer 0-20% by weight filler 0~20% by weight other additives

[0033] Composition Example 3 Particularly preferred composition 45~63% by weight binder 38-53% by weight plasticizer 0-17% by weight filler 0~15% by weight other additives

[0034] Stabilizers, co-stabilizers, colorants and / or fillers are examples of other additive substances that may be used, if desired.

[0035] Mixing example 1 Yellow molding compound 51% by weight E-PVC and S-PVC 42% by weight ATBC based plasticizer 6% by weight stabilizer 0.5% by weight filler 0.5% by weight Pigment Yellow 83

[0036] Mixing Example 2: Molding compound that is transparent after curing 48% by weight E-PVC and S-PVC 52% by weight ATBC based plasticizer

[0037] Prior Art Comparative formulations described in DE 10 2005 059 143 A1 59wt% PVC 24% by weight citric acid based plasticizer 1% by weight stabilizer 7% by weight Co-stabilizer 4% by weight filler 1% by weight Pigment Red 254

[0038] Preferably used phthalate-free plasticizers are based on citric acid and / or adipic acid.

[0039] The desired consistency of the compound can be easily adjusted by varying the binder content and / or plasticizer content.

[0040] The present invention will now be described in more detail with respect to the molding compound using the following table.

[0041] [Table 1]

[0042] In comparison to the prior art, the compounds described herein that have not yet been oven cured have been found to show significantly less increase in hardness when stored at 40° C. over time (30 or 90 days), as shown in Table 1.

[0043] [Table 2]

[0044] These high breaking strengths were measured and confirmed using a texture analyzer. Round bar fragments 10 cm long and 1 cm in diameter were prepared as test specimens.

[0045] The molding compounds produced according to the invention are used in automobile manufacturing, household goods, medical equipment, toys and the food industry, as well as in accessories to the aforementioned applications.

[0046] Articles and objects formed using molding compounds produced according to the invention are cured after molding by the action of heat.

[0047] A method for producing a molding compound consisting of at least a binder and a plasticizer, the binder and the plasticizer being formed as a plastisol, the plastisol being substantially composed of PVC and the plasticizer, is carried out by subjecting a PVC powder and an amount of the plasticizer, optionally together with other additives and / or additives, to a mixing step, the mixing step being carried out at a mixing temperature of 55-70°C.

Claims

1. 1. A method for producing a molding compound comprising at least a binder and a plasticizer, said binder and said plasticizer being formed as a plastisol, said plastisol consisting essentially of PVC and the plasticizer, said method comprising: The PVC powder and a certain amount of plasticizer, optionally together with other additives and / or additives, are subjected to a mixing process, said mixing process being carried out at a mixing temperature of 55-70°C. By doing so, the plasticizer is formed as a phthalate-free plasticizer; the phthalate-free plasticizer is based on citric acid; The method according to claim 1, wherein the plasticizer content is 32 to 60% by weight.

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

3. The molding compound comprises at least 20 to 68% by weight binder 32-60% by weight plasticizer 0-40% by weight filler 0-20% by weight Other additives 2. The method of claim 1, comprising:

Images