MASTER BATCH TO BE ADDED TO A THERMOPLASTIC RESIN

Abstract: Master batch to be added to thermoplastic resin, which can be used universally. Additive particles are dispersed in a vehicle comprising an aromatic resin which can be dispersed in the thermoplastic resin, and/or a modified alkyd free from oil.

Description: MASTER BATCH TO BE ADDED TO A THERMOPLASTIC RESIN The present invention relates to a master batch to be added to a thermoplastic resin, including additive particles dispersed in a vehicle- Regarding such a master batch supplied in pelleted or granulated form, the requirement is that the master batch has a granular size which is commensurate with the granular size of the thermoplastic resin (basic raw material) which the master batch is to be mixed with. The reason for the requirement of the same granular size as that of the basic raw material is i .a. that granules of smaller size than the granules of the basic raw material fall through in the material magazine of the machine wherein the material is being used such as an injection moulding machine or an extruder and thus provide a higher concentration of the additive in the lower portion of the magazi ne .than in the upper portion thereof. The material falling through in this way is due to movements of the material in the magazine during the supply thereof to the plasticizing unit of the machine as well as occurring shaking and vibration of the machine. Another requirement regarding the master batch is that it should be possible to use it not only together with basic raw materials of an arbitrary granular size but also together with different types of thermoplastic resin. The master batches made to-day are intended for a specific type of thermoplastic resin the adjustment of the master batch to different types of thermoplastic resin being made by using different types of vehicles in the master batch. It is common that the thermoplastic resin used as vehicle in the master batch is the same as that which the master batch is to be mixed with. Thus, if a product is to be made of PVC this material is also -BU REA U O.V.PI used as vehicle in the master batch, and if the product is to be made of polystyrene or polyolefine the vehicle used is polystyrene and polyolefine, respectively, and so on. Accordingly, a big selection of master batches is required in order to cover the different needs that may arise in the production of thermoplastic resin products, i.e. one type of master batch for each type of thermoplastic resin, and con¬ sidering the fact that there is a choice of several different thermoplastic resins when manufacturing products of different types, this means that the plastic manufacturers have to keep a stock of different types of master batch the number of which is the same as the number of thermoplastic resins used. Confusion may easily occur and may be fatal because a master batch having a vehicle of a specific thermoplastic resin cannot be mixed with other thermo¬ plastic resins. The invention relates particularly to a master batch in the form of a toner including colour pigment particles as an additive said particles being dispersed in the vehicle. Other examples of additives or fillers which can be included into the master batch are UV stabilizers, lubricants, organic peroxides, pi asticizer heat stabilizers and flame-resistant agents. Particularl as far as additives are concerned, which are of the typ having two or more components, such as foaming agents, it may be important that at least one of the components is supplied and added as a master batch. Several additives can appear in one and the same master batch, e.g. colour pigments in combination with other fillers. Master batches in the form of a toner are manu¬ factured in such a way that there is added to the vehicl which thus has been chosen with regard to the intended use of the toner, between 20 and 50 per cent by -BOR i. weight colour pigment particles together with certain lubricants. This mixture is plasticized in an extruder and is pelleted or granulated to a toner (master batch) intended especially for the thermoplastic resin included in the toner. The toner thus produced is then used for colouring the thermoplastic resin used as a basic raw material in the plastic product factory where the final product is being manufactured the toner being added in an amount of 1 or 2 per cent in order to obtain the desired colour shade of the final plastic product. It should be mentioned here that besides the • colouring of the basic raw material by the use of a toner including colour pigment particles dispersed in a vehicle the .so-cal 1 ed dry colouring exists which implies that colour pigment particles are added in the plastic product factory directly to the thermoplastic resin used as basic raw material , by means of a mixer so that the comminuted colour pigment adheres to the granulated plastic resin. However, this method is objectionable from an environment point of view because the colour pigment creates an unhealthy dust emission. A supply of the colour pigment to the basic raw material , which is completely free from dust, therefore is aimed at to-day and in this respect the use of a toner of the type referred to herein has proved to be preferable. As would be clear from the discussion above there is, however, a need for a master batch, e.g. a dust- -free toner, which can be used universally for different types of thermoplastic resin s.o that the many different types or qualities which exist now can be reduced to a single type and quality. The requirements that have to be set regarding the vehicle of such a master batch that can be used universally as an additive to thermo¬ plastic resins are primarily as follows: l . The vehicle should be able to absorb additive par- OMPI tides up to 50 - 70 per cent of its own weight. 2. The vehicle should have a pi asticization temperature below the plasticization temperature of the thermoplastic resin used as basic raw material , and latest at a temperature at the plasticization temperature of the basic raw material it should have a lower viscosity than the basic raw material. 3. The vehicle should be able to supply the additive to the basic raw material and should be able to be dispersed therein without appreciable effect on the physical or chemical properties of the final product. 4. The vehicle should have a coherent structure in cold condition so that the product can be pelleted or granulated to the same size as the basic raw material. 5. The vehicle, moreover, should have a lubricat¬ ing or stabilizing effect. According to the invention, it has been found that a master batch which can be universally used as an additive to thermoplastic resin can be obtained, compris ing additive particles dispersed in a vehicle, wherein the vehicle provides the five properties listed above, if the vehicle comprises an aromatic resin which can be dispersed in the thermoplastic resin, or a resin modifie alkyd which can be dispersed in the thermoplastic resin, of the nature otherwise appearing from the characterizin cl ause of claim 1. The invention will be described in more detail belo with reference to illustrative examples. EXAMPLE 1 A suitable vehicle in a toner according to the invention as far as dark colour shades are concerned is the aromatic resin marketed by AB Nynas-Petrol eu under the registered trademark Nyomer. This aromatic resin is manufactured by the method described in the Swedish patent specification 7406252-2 and the addition thereof 7512352-1 , and it has such a molecular composition that it can be dispersed to the necessary extent in the great majority of thermoplastic resins presently known without significantly impairing the original properties of the basic raw material wherein the toner containing Nyomer is being dispersed. In producing the toner according to the invention colour pigment particles of the desired colour are dis¬ persed in a vehicle comprising Nyomer in a conventional manner the colour pigment comprising 50 to 70 per cent of the weight of the vehicle depending on the shade desired. The mixture of colour pigment and vehicle is plasticized in an extruder and pelleted or granulated in a conventional manner. The toner thus obtained has been found to have a dispersing, lubricating and stabilizing effect when added to the thermoplastic resin used as basic raw material . Nyomer per se is dark brown and therefore the use thereof as a vehicle for colour pigment particles is limited to dark colour shades. On the other hand, it then provides a reduction of the costs thanks to the fact that it contributes to the colouring the consump¬ tion of expensive colour pigment material thus being reduced . A prob.lem encountered in outdoor use of e.g. brown colour shades is the limited resistance of the plastics material to heat due to sun radiation. The increased heat absorption of the plastics material i.a. if it has a brown tint provides plastic movements in the material so that the product often will change its form due to equalization of inherent strains in the material . One reason for form changes at sun radiation particularly UU E AZΓ OMPI of products having a brown tint is the fact that iron oxide pigments are included. Plastics material coloured with brown toner according to the invention, which does not contain iron oxide but is given its colour solely by the vehicle comprising Nyomer, has been found to be shape-permanent for outdoor use and, moreover, the colouring of the plastics material obtained by such a toner is light-proof. The toner according to the invention thus is a good UV stabilizer against bleaching of given colour shades due to the ultraviolet rays con- • tained in the sunlight. Nyomer has a further property when used as vehicle in a toner i.a. as far as rigid PVC is concerned. In that case, the vehicle constitutes a so-called high- -molecular plasticizer, which means that the vehicle has the property of plasticizing rigid PVC at the plasticization temperature without a corresponding plasticity arising in cold condition. Rigid PVC thus remains rigid at normal temperatures of use but the vehicle has the ability to plasticize the PVC in the stage of plasticization at the plasticization temperatur which facilitates the supply of the colour pigment and also facilitates the plasticization of the basic raw material without the final product being plasticized. Because rigid PVC definitely is most difficult to handle of modern thermoplastic resins presently known and because Nyomer influences rigid PVC as men¬ tioned above it can be concluded therefrom that the function is the same as far as most other thermoplastic resins are concerned. Summarizing, it thus can be established that the use of Nyomer or other similar aromatic resin within the scope of the invention as defined in the claims provides a dust-free toner which can be used universally and in which the vehicle constitutes an internal as well as an external lubricant when the toner is supplied and dispersed. The toner, moreover, operates as a stabilizer against deterioration of the final product in some cases and as strain equalizing stabilizer in other cases in order to relieve strains that otherwise could be embodied in the product proper during the transition thereof from plastic condition to cold condition. Moreover, the vehicle operates as a high-molecular plasticizer, particularly in connec- tion with rigid PVC. EXAMPLE 2 In a toner according to the invention in case of light and snow-white colour shades where Nyomer cannot be used the resin-modified alkyd which is marketed by Bergviks Hartsprodukter AB under the trademark Berigid 100 is a suitable vehicle. This resin-modified alkyd is produced by the method described in the Swedish patent specification 356,060 and although it has been developed primarily to be mixed with polyvinyl chloride material it has been found that it is suitable also for addition to entirely different plastics materials such as polystyrene and polyethylene. For example a white pigment can have the following composition when Berigid 100 is used: White colour pigment, Ti O 30 % Berigid 100 35 % Tall oil 10 % EVA 20 % Stearic acid 2.5 % Calcium stearate 2.5 % The stearic acid prevents the thermoplastic resin from adhering in the machine in which it is worked. The stearate which can be e.g. calcium, zinc or aluminium stearate improves internal and external lubrication of the thermoplastic resin. The production of the toner by applying this recipe can be performed in the same manner as described above in connection with the use of Nyomer. Berigid 100 per se has a plasticization temperatur of about 110°C and can be modified as stated below in order to obtain different plasticization temperatures: For plasticization temperature 71°C Berigid 100 70 % Tall resin 20 % Tall oil 1 0 % For plasticization temperature 67°C Berigid 100 67 . 5 % Tall resin 20 % Tall oil 1 2 . 5 % For plasticization temperature 62°C Berigid 100 65 % Tall resin 20 % Tall oil 1 5 % To the mixtures listed above there can be added colour pigment particles in a concentration which is more than 50 per cent. If required, also some wax can be added. Berigid 100 can also be modified in order to chang the plasticization temperature thereof by adding ethyl- vinyl acetate (EVA) or a similar polymer. For example EVA can be obtained from Du Pont de Nemours under the trademark Elwax in different variants which influence the plasticization temperature in different ways. For example the following modifications of Berigid 100 can be obtained: For plasticization temperature 80°C Berigid 100 70 % Elwax 220 30 % For plasticization temperature 110 C Berigid 100 70 % Elwax 150 30 % For plasticization temperature 130°C Berigid 100 70 % Elwax 240 30 % In these modifications the change of the plasticization temperature obtained is dependent on the ratio between ethyl and vinyl in the ethylvinyl acetate polymer (Elwax). Berigid 100 and Nyomer have such properties that they can be mixed with each other as far as specific colour shades are concerned. To a toner which is based on Berigid 100 Nyomer thus can be added in order to obtain a darker colour shade. It may be of interest to add to a toner which is based on Nyomer, Berigid 100 in order to obtain a higher finish, improved gelation effect and increased capacity. In the latter case it is sufficient with an addition of 5 to 30 per cent to the total Nyomer recipe which then may contain up to 50 per cent carbon black. At such a high toner con¬ centration gelation aid is of extremely great importance. The modified mixtures with Berigid 100, mentioned above also lower the plasticization temperature of Nyomer in case it is included in the toner, the property of Nyomer acting as a universal vehicle being maintained. By the master batch according to the invention the following advantages are obtained: 1. The master batch can be used universally in known thermoplastic resins. 2. By the addition of the master batch the surface finish of the final product is improved because the surface will be smooth and brilliant due to the fact that the thermoplastic resin flows more easily. The surface obtained is -BUREAU _ 01ΪLF5 well suited for heat embossing and screen printing. 3. By the addition of the master batch the - strength and other physical properties of the final product are improved due to an improved mixing and gelation of the thermo¬ plastic resin. 4. The master batch has a rheol ogy-i proving effect, i.e. it facilitates processing. 5. The vehicle is non-toxic because it does not contain heavy metals or other constituents which are known to be toxic. 6. The water absorption of the final product is reduced, which in turn involves an improved cold resistance. 7. The final product has improved shape perma¬ nence. 8. The final product has improved durability due to reduced outward migration of additive and thereby is better suited for contact with food-stuffs and less dangerous for those who work with the product e ve ry day (some additive can be toxic per se) . 9. A product which has been coloured with a toner in the form of a master batch according to the invention does not give its colour off. 10. The master batch can be used in regenerating plastics scrap in order to improve the proper¬ ties of the generate by having a positive influence on the reconstruction of the polymer or the polymers of the plastics scrap, probabl by initiating a polymerization or in similar ways . The master batch according to the invention can include any additive for the addition of these additives -^U O to a thermoplastic resin, but the invention primarily has been developed for master batch in the form of a toner wherein the additive comprises solely a colour pigment or a colour pigment combined with other additives for influence on the properties of the thermoplastic resi n. "BU EAU OMPI

Claims: CLAIMS 1. Master batch to be added to a theromopl astic resin, which can be used uni versal ly, compri si ng additive particles dispersed in a vehicle, c h a r a c t e r - i z e d in that the vehicle comprises an aromatic resin which can be dispersed in the thermoplastic resin and is produced of an oxidized mineral oil distillate and/or an oxidized solvent extract of mineral oil distillate including aromatically bound carbon, the ' content of the aromatic compound corresponding to a minimum VGC value (VGC = Viscosity Gravity Constant) according to ASTM D 2140 of 0.85 and having an average molecular weight of 150 to 600, and/or an alkyd free from oil and modified by esterifi cation of resin acids, which has been produced of a resin material including more than 95 per cent by weight of free resin acids, and which has a minimum plasticization temperature of 90°C as measured according to the ball-and-ring method. 2. Master batch according to claim 1, c h a r a c t e i z e d in that the amount of additive particles comprises 5 to 80 per cent, preferably 30 to 70 per cent, of the vehicle weight. 3. Master batch according to claim 1 or 2, c h a r a c t e i z e d in that it is granulated to a granular size which is substantially commensurate with the granular size of the thermoplastic resin to which the master batch is to be added. 4. Master batch according to claim 1 wherein the vehicle comprises the modified alkyd, c h a r a c t e r i z e d in that the alkyd is mixed with ethyl vinyl acetate polymer or a similar polymer for controlling the plasticization temperature of the alkyd. 5. Master batch according to any of claims 1 to- - ■ 4, c h a r a c t e r i z e d in that it has the fo of a dust-free toner including colour pigment particles "BU O as additive, for colouring the thermopl astic resi n IJUREIΓ OMPI

Inventors: AKESSON T, ROSEN K
Applicants: AKESSON T, ROSEN K
Application year: 1978
Main classification: D06P1
IPC codes: C08J3, C08K9