Polyolefin color masterbatch and method for preparing the same

Abstract

The application discloses a polyolefin color master batch and a preparation method thereof. The polyolefin color master batch is prepared from the following raw materials in mass fraction: 50-80% of pigments, 1-2% of a modifier, 1-5% of a dispersant, 1-3% of other additives, and the rest of carrier resin. The modifier contains a thiazole ring structure. The color master batch disclosed by the application can load high-concentration pigments, has good dispersity, small color difference, good weather resistance, and has a smooth surface without air holes, black spots or color powder spots.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of plastic coloring, in particular to a polyolefin color master batch and a preparation method thereof. BACKGROUND

[0002] The color master batch coloring method is the most important and the most common method in the coloring of plastic products. The color master batch, i.e. pigment preparation, is an aggregate prepared by uniformly loading super-constant colorants in resin through a special method, also called pigment concentrate, which is a new type of high-efficiency coloring preparation for special high polymer materials. The primary condition for the application of the color master batch to plastics is to enable the pigment to be uniformly dispersed in the plastic, to give the plastic rich color, and at the same time, not to affect other properties of the product. The dispersion of the pigment not only affects the appearance and processability of the colored product, but also directly affects the quality of the colored product. Poor dispersion of the pigment can easily cause spots or streaks on the surface of the colored product, and the gloss, color and transparency of the colored product will also be affected.

[0003] In order to improve the strength, transparency, color depth and brightness of the product and improve the utilization rate of the pigment, it is necessary to reduce the particle size of the pigment, i.e. to improve the dispersibility of the pigment. Whether the pigment can obtain the best dispersion in the color master batch coloring process depends on three factors in the process, i.e. the dispersibility of the pigment itself, efficient processing equipment or efficient dispersant.

[0004] Among various process methods, efficient dispersant is indispensable, and the dispersant has become the main additive in the color master batch. In the entire processing stage of the color master batch, the dispersant can penetrate into the gaps and pores in the pigment agglomerates, reduce the surface tension and mutual attraction of the particles, transfer the shear force of the equipment, and effectively open the agglomerated particles. In addition, the dispersant also coats the surface of the pigment, uses charge repulsion, space blocking or entropy effect to prevent the fine pigment particles from agglomerating, and plays a stabilizing role. The addition of the dispersant can also accelerate the wetting between the polymer and the pigment, reduce the surface tension between the polymer and the pigment, increase the affinity between them, and improve the compatibility of the pigment and the resin. The dispersant can also improve the flowability of the color master batch, increase the yield and improve the processing performance of the product.

[0005] The high concentration of the pigment in the color master batch is the development trend of the color master batch, and the content of the pigment is as high as 70% to 80%, and the content of the carrier resin and other substances is only about 20%. The higher the content of the pigment in the color master batch, the more difficult the dispersion, and the manufacturing difficulty also increases. The core of the development of the color master batch technology lies in the mutual compatibility of the pigment, the dispersant and the carrier, the key lies in improving the dispersibility of the pigment, and the goal lies in improving the pigment content and the coloring efficiency in the color master batch. Developing a new type of color master batch with high efficiency, easy dispersion, non-toxicity and good stability is the future development trend. SUMMARY

[0006] The application aims to provide a high-concentration polyolefin color master batch with good dispersibility.

[0007] To achieve the above objective, the application adopts the technical scheme of a polyolefin color master batch made of the following raw materials by mass fraction: 50-80% pigments, 1-2% modifier, 1-5% dispersant, 1-3% other additives, and the rest carrier resin, wherein the modifier contains a thiazole ring structure.

[0008] As a preferred, the molecular weight of the modifier is not more than 3000.

[0009] As another preferred, the modifier is a colorless liquid.

[0010] As another preferred, the modifier also has a silicon group.

[0011] As another preferred, the modifier is 2-(trimethylsilyl)thiazole.

[0012] As another preferred, the dispersant contains a C=C double bond structure.

[0013] As another preferred, the dispersant is one of polyethylene wax or polypropylene wax.

[0014] Further preferably, the pigments are organic pigments, and the carrier resin is one of low-density polyethylene or high-pressure polyethylene.

[0015] A preparation method of a polyolefin color master batch, comprising the following preparation steps: S1: mixing pigments with a modifier, sufficiently grinding, drying, and crushing to micron-level particle size to obtain a mixture; S2: heating and plasticizing a carrier resin in a mixing device, adding a dispersant, the mixture, and other additives after the carrier resin is melted, mixing until the pigments are uniformly dispersed, adjusting the mixing device to discharge and making 3-5 mm color master batch.

[0016] As another preferred, the S1 step specifically comprises: weighing a certain amount of the pigments, dropwise adding the modifier and sufficiently grinding, drying in a dryer after grinding, and crushing to micron-level particle size by a laboratory air powder machine to obtain the mixture.

[0017] Compared with the prior art, the application has the following beneficial effects:

[0018] (1) The color master batch of the application uses a thiazole modifier, which is compounded with a dispersant to effectively improve the uniformity of pigment dispersion in the color master batch;

[0019] (2) The modifier of the color master batch of the application is a thiazole structure, and a silicon group is introduced, which can improve the weather resistance of the color master batch and the dispersibility of the pigments;

[0020] (3) The color master batch of the application has good dispersibility and high concentration.(3) The color master batch of the present application has a pigment concentration of 50% to 80%, the pigment is uniformly dispersed, the surface of the color master batch is smooth without air holes, and no black spots or color powder spots appear. DETAILED DESCRIPTION

[0021] Hereinafter, the present application will be further described in conjunction with specific embodiments, and it should be noted that the embodiments described below or the technical features between the embodiments can be combined in any manner to form new embodiments without conflict.

[0022] The terms "comprising" and "having" and any variations thereof in the specification and claims of the present application are intended to cover not exclusively including, for example, a process, method, system, product or device comprising a series of steps or units does not have to be limited to those steps or units clearly listed, but can include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0023] The polyolefin color master batch of the present application comprises the following raw materials by mass fraction: 50% to 80% pigment, 1% to 2% modifier, 1% to 5% dispersant, 1% to 3% other additives, and the rest is carrier resin.

[0024] The polyolefin color master batch of the present application is a high-concentration polyolefin color master batch, wherein the pigment concentration is more than 50%. The high-concentration color master batch can make the color of the colored product more bright and vivid, reduce color difference, and make the colored product more beautiful.

[0025] The dispersant and the carrier resin must have good compatibility. Polyethylene wax, polypropylene wax, paraffin wax, polyamide wax, white mineral oil and other polymers are selected, which can not only improve the fluidity of the system, but also increase the yield. In addition, some low-cost polymers are selected, which is beneficial to reduce the production cost of the color master batch.

[0026] In some embodiments, the dispersant contains C=C double bond groups, which can have better compatibility with polyolefin plastics, so that the pigment is more uniformly distributed. In addition, it can also synergistically increase the dispersibility of the pigment with the modifier.

[0027] In some preferred schemes, the dispersant is any one of polyethylene wax or polypropylene wax.

[0028] It is well known that the melt viscosity of the carrier resin in the color masterbatch is high, and the compatibility with the surface of the pigment is poor. When the masterbatch system with dispersant is processed, the dispersant melts first before the resin, and is coated on the surface of the pigment. Because the viscosity of the dispersant is low and the compatibility with the pigment is good, the pigment is more easily wetted, and can penetrate into the pores inside the pigment agglomerates, weaken the cohesion, so that the pigment agglomerates are more easily opened under the action of external shear force, and the newly generated particles can be quickly wetted and protected, thereby promoting the dispersion of the pigment in the color masterbatch, and allowing a higher pigment concentration. Therefore, for polyethylene wax used as a dispersant for color masterbatch, the melting point must be lower than the melting point of the carrier resin. Having a suitable low melting point becomes one of the important properties of polyethylene wax.

[0029] The modifier of the present application is a thiazole reagent, preferably a colorless liquid thiazole reagent. Thiazole compounds are composed of a thiazole ring and one or more side chains, wherein the thiazole ring is a five-membered heterocyclic ring composed of one sulfur atom and two nitrogen atoms. Thiazole ring is an important class of five-membered aromatic heterocyclic ring, containing nitrogen and sulfur heteroatoms, with rich electrons, easy to form hydrogen bonds, coordinate with metal ions, and π-π stacking, electrostatic and hydrophobic interactions and other non-covalent bond interactions. This structure endows thiazole compounds with many special properties and has wide potential applications in many fields.

[0030] The main feature of thiazole derivatives is their extremely high stability, with very low free energy, not easy to hydrolyze, and can maintain its activity even in low temperature and high humidity environment, and not easy to chemical reaction.

[0031] In addition, thiazole derivatives have certain antimicrobial properties, and can play an antibacterial role in plastic products, improving the cleanliness and hygiene of plastic products.

[0032] In some embodiments, the molecular weight of the modifier is not more than 3000, and preferably the modifier with lower molecular weight has better compatibility with the dispersant or carrier resin.

[0033] The modifier of the present application is a colorless liquid, which can wet the pigment, protect the color of the pigment, avoid the agglomeration of pigment particles, improve the compatibility of the dispersant and the pigment, so that the pigment can be dispersed more finely in the dispersant, thereby facilitating the increase of the pigment content in the color masterbatch and the preparation of high-concentration color masterbatch.

[0034] In the preferred scheme, the modifier of the present application has a thiazole ring and a silicon group, and the silicon group has stable performance, which can improve the heat resistance and weather resistance of the color masterbatch to a certain extent, so that the prepared color masterbatch can still withstand a certain processing temperature and weather resistance when added to polyolefin plastics.

[0035] The modifier of the present application has a thiazole ring and a silicon group, which can be well inter-soluble with dispersants such as polyethylene wax and polypropylene wax, thereby improving the dispersion degree of pigments. The dispersion and inter-solubility of pigments can be improved, and the content of pigments in the color master batch can be increased, thereby obtaining high-concentration color master batch. The introduction of the silicon group is also beneficial to improving the weather resistance of the color master batch.

[0036] In some embodiments, the modifier is 2-(trimethylsilyl)thiazole.

[0037] For polyolefin color master batch, high melt index low density polyethylene (LLDPE) or high pressure polyethylene (LDPE) is generally selected as the carrier resin, which has good processing fluidity, and is blended with the colored resin to adjust the viscosity of the system, thereby playing a role in infiltrating and dispersing pigments, minimizing the amount of dispersant, and even achieving good dispersion effect without dispersant, and ensuring that the performance of the colored product does not decrease.

[0038] In some embodiments, the pigment can be an organic pigment or an inorganic pigment. The organic pigment can be colored lake red C, pyrazolone red, vat red, benzidine yellow, monoazo orange, dioxazine violet, phthalocyanine blue, carbon black, phthalocyanine green. The inorganic pigment is iron oxide, cadmium selenide, titanium oxide, chromium yellow, molybdenum chromium red, cadmium sulfide, titanium yellow, ultramarine blue, chromium oxide green.

[0039] In some preferred embodiments, the pigment is an organic pigment, which can be better inter-soluble with the modifier.

[0040] Other additives are auxiliary ingredients in the process of plastic processing or coloring. The filler is derived from a wide range of inorganic mineral materials. The presence of the filler can increase the relative yield of the plastic, increase the strength and heat resistance of the plastic, and significantly reduce the cost of the plastic product, so that the plastic formulation has better processing performance, better physical properties, and rich mechanical properties and other use properties. Other additives are generally chemically inert and can stably exist in the main components of the resin. As a dispersed phase in the plastic matrix, the content of the filler is higher than that of other components. In order to obtain more use value, the filler should meet the selection conditions of wide source, low cost, high content, and obvious strengthening effect.

[0041] In some embodiments, the other additive can be a reinforcing agent, an extender, an ultraviolet light resistant filler, a conductive filler, an impact resistant filler, a flame retardant filler, a magnetic filler, a sensory filler, an anti-blocking filler, etc. The specific selection of other additives is based on the actual application of the plastic product. There are many examples in the prior art, which will not be repeated here.

[0042] The present application also provides a preparation method of the polyolefin color master batch, which comprises the following preparation steps:

[0043] S1: mix the pigment with the modifier, dry after grinding, crush to micron level particle size, and obtain the mixture;

[0044] S2: heat and plasticize the carrier resin in the mixing device, add the dispersant, the mixture and other additives after the carrier resin is melted, mix until the pigment is uniformly dispersed, adjust the mixing device to discharge and make 3-5mm color master batch.

[0045] In some embodiments, the S1 step is specifically: weigh a certain amount of pigment, drop the modifier drop by drop and grind thoroughly, send to the dryer after grinding, crush to micron level particle size with a laboratory air powder machine, and obtain the mixture;

[0046] In some embodiments, the S2 step is specifically: according to the processing temperature of the processed resin, heat the double roller mixing machine to 105℃, start to plasticize the carrier resin after the temperature is stable, and the plasticizing time is 5-10min; add the dispersant polyethylene wax after the carrier resin is melted, mix for 2-5min, add the mixture and other additives again, and mix again during the mixing process. A scraper can be used to scrape the material left and right to make the material mix quickly. After the pigment is well dispersed in the carrier resin, adjust the double roller spacing of the mixing machine to 1mm, reduce the double roller speed, discharge, and obtain 1mm thin slices. Use scissors to cut the thin slice sample into 3-5mm small particles to obtain the color master batch;

[0047] The preparation method of the polyolefin color master batch of the application has simple steps, strong operability, does not need to introduce additional devices and instruments, and saves production cost.

[0048] Example 1

[0049] S1: weigh a certain amount of pigment, drop the modifier 2-(trimethylsilyl)thiazole drop by drop and grind thoroughly, send to the dryer after grinding, crush to micron level particle size with a laboratory air powder machine, and obtain the mixture;

[0050] S2: according to the processing temperature of the processed resin, heat the double roller mixing machine to 105℃, start to plasticize the carrier resin LDPE after the temperature is stable, and the plasticizing time is 5min; add the dispersant polyethylene wax after the carrier resin is melted, mix for 2-3min, add the mixture and the flame retardant filler again, and mix again during the mixing process. A scraper can be used to scrape the material left and right to make the material mix quickly. After the pigment is well dispersed in the carrier resin, adjust the double roller spacing of the mixing machine to 1mm, reduce the double roller speed, discharge, and obtain 1mm thin slices. Use scissors to cut the thin slice sample into 3-5mm small particles to obtain the color master batch;

[0051] The mass fraction of the pigment is 50%, the mass fraction of the modifier is 2%, the mass fraction of the dispersant is 5%, the mass fraction of other additives is 3%, and the rest is the carrier resin.

[0052] Example 2

[0053] The polyolefin color master batch of the present example has the same raw material composition and preparation method as that of Example 1, except that the color master batch of the present example is composed of the following raw materials by weight: 80% of the pigment, 1% of the modifier, 1% of the dispersant, 1% of other additives, and the rest of the carrier resin.

[0054] Example 3

[0055] The polyolefin color master batch of the present example has the same raw material composition and preparation method as that of Example 1, except that the carrier resin selected for the color master batch of the present example is low-density polyethylene LLDPE.

[0056] Example 4

[0057] The polyolefin color master batch of the present example has the same raw material composition and preparation method as that of Example 1, except that the modifier selected for the color master batch of the present example is thiazole.

[0058] Comparative Example 1

[0059] The polyolefin color master batch of the present example has the same raw material composition and preparation method as that of Example 1, except that the color master batch of the present example does not add a modifier, and uses a mixture of pigments, dispersants, other additives, and carrier resin.

[0060] Comparative Example 2

[0061] The polyolefin color master batch of the present example has the same raw material composition and preparation method as that of Example 1, except that the color master batch of the present example does not add a dispersant, and uses a mixture of pigments, modifiers, other additives, and carrier resin.

[0062] Comparative Example 3

[0063] The polyolefin color master batch of the present example has the same raw material composition and preparation method as that of Example 1, except that the modifier in the present example is replaced by 3-(trimethylsilyl) aniline.

[0064] Comparative Example 4

[0065] The polyolefin color master batch of the present example has the same raw material composition and preparation method as that of Example 1, except that the dispersant in the present example is replaced by white mineral oil, which does not contain a C=C double bond structure.

[0066] Performance test:

[0067] Color masterbatch film preparation: the pigment content in the film is 1%, the temperature of the two-roll open mill is increased to 105°C, the color masterbatch prepared in each example and each comparative example is mixed with polypropylene according to the mass ratio, the color masterbatch and polypropylene are mixed, and after the pigment is well dispersed in the resin, the open mill presses the sample into a thin sheet of about 1mm.

[0068] Plastic sample preparation: polypropylene is selected as the colored resin, and the pigment content in the sample of each example and each comparative example is 0.5%, the temperature of the feeding section is set to 180°C, the temperature of the melting section is set to 200°C, the temperature of the homogenizing section is set to 200°C, and the temperature of the die head is set to 180°C.

[0069] 1. Evaluation of pigment dispersibility in polyolefin plastic: the color masterbatch prepared in each example and each comparative example is added to polyolefin, a 2.5mm thick sample is obtained by injection molding, and then a film is pressed at 170°C, the number of pigment particles with a diameter of 0.5mm, 2μm, 10μm and 30μm or more is counted, and the dispersibility is evaluated, and the dispersibility rating is shown in Table 1.

[0070] Table 1 Dispersibility rating

[0071] Rating 5 4 3 2 1 Average particle diameter / μm 1.0 1.0 1.0 1.0 1 <5 5 10～30 30～100 >100

[0072] 2. Total color difference: according to Q / SYRD-R-2014 polyolefin color masterbatch enterprise standard, four standard color plates are taken to measure the L, a, b values with a color difference meter, and four sample color plates are taken to measure the L, a, b values to obtain the total color difference. The total color difference is less than 0.5 for qualified.

[0073] 3. Rheological property test: the torque rheometer is used to test the torque-time curve at 160°C and 60r / min, and the rheological property is evaluated according to the balance torque and the time required to reach the maximum torque.

[0074] 4. Color strength test: the color strength of pigment refers to the amount of pigment required for a certain color product, which is expressed by the percentage of the color strength of the standard sample. That is, 1g of standard sample is taken, Ag of white pigment is added, and a mixture of a certain color is prepared. Then, 1g of the pigment to be tested is taken, and white pigment is added until the color observed under the standard light source is the same as that of the standard sample mixture. If the white pigment used is B g, the color strength I of the pigment is:

[0075] I = B / A*100%

[0076] The tinting strength of the pigment is not only related to its properties, but also to the dispersion degree of the pigment. The dispersion degree mainly refers to the degree of refinement of the pigment, and the greater the dispersion degree, the higher the tinting strength, but there is a maximum value, and the tinting strength decreases when the value is exceeded. The above is the standard for the tinting strength of ink and paint. The standard for the tinting strength of plastic pigments suggests that different amounts of resin are added to the standard sample and the sample to measure the ratio of the same color depth, that is, A is the amount of resin added to the standard color plate, and B is the amount of resin added when the color depth is close to A.

[0077] 5. Weather resistance test: the test method is carried out according to GB / T9344-1988, and the color difference ΔE of the sample after 1000h exposure to xenon light source is taken as the evaluation index.

[0078] The performance test results are recorded in Table 2 below.

[0079] Table 2 Performance test results of color master batch

[0080]

[0081] From the test results in Table 2, it can be seen that the polyolefin color master batch prepared in this embodiment has good dispersion, small color difference compared with the standard color plate, strong tinting strength and good weather resistance.

[0082] The modifier added in this application has a lubricating function, which can increase the surface tension and mutual attraction between pigments, reduce the agglomeration of pigment particles, and after being added to the dispersant and carrier resin, it has a lubricating effect on the color master batch. The better the lubricating effect, the lower the balance torque, and the longer the time required to reach the maximum torque.

[0083] From the test results of Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3, it can be seen that the thiazole structure modifier and polyethylene wax or polypropylene wax dispersant containing C=C double bond are compounded creatively in this application, which can obtain good dispersion under the condition of high pigment concentration. In addition, the introduction of silicon groups into the thiazole structure can also improve the dispersion and weather resistance of the pigment, and the polyolefin product prepared is durable.

[0084] The polyolefin color master batch of the present application improves the dispersion of pigments under the condition of loading high concentration of pigments by using modifiers, dispersants and carrier resins, and the preparation method is simple, easy to operate and economically applicable.

[0085] The foregoing describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above-described embodiments, and the above-described embodiments and descriptions in the specification are only the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection claimed by the present application is defined by the appended claims and their equivalents.

Claims

1. A polyolefin masterbatch, characterized in that, It is made from the following raw materials by mass fraction: 50%~80% pigment, 1%~2% modifier, 1%~5% dispersant, 1%~3% other additives, and the remainder is carrier resin; the modifier is 2-(trimethylsilyl)thiazole, and the dispersant is one of polyethylene wax or polypropylene wax.

2. The polyolefin masterbatch as described in claim 1, characterized in that, The pigment is an organic pigment, and the carrier resin is either low-density polyethylene or high-density polyethylene.

3. The method for preparing polyolefin masterbatch as described in claim 1 or 2, characterized in that, The preparation steps include the following: S1: Mix the pigment with the modifier, grind thoroughly, dry, and pulverize into micron-sized particles to obtain a mixture; the modifier is 2-(trimethylsilyl)thiazole; S2: Heat the mixing device to plasticize the carrier resin. After the carrier resin melts, add the dispersant, the mixture and other additives. Mix until the pigment is evenly dispersed. Adjust the mixing device to produce sheets and make 3-5 mm color masterbatch. The dispersant is either polyethylene wax or polypropylene wax.

4. The preparation method according to claim 3, characterized in that, The S1 step specifically involves: weighing a certain amount of the pigment, adding the modifier dropwise and grinding thoroughly, then sending it to a dryer to dry, and pulverizing it to a micron-sized particle size using a laboratory air powder mill to obtain the mixture.

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