Acrylonitrile-butadiene-styrene resins are used in a wide range of applications and are commonly found in applications such as electrical appliances, toys, office equipment, sanitary ware, etc. Coloring of ABS resins is generally done in a color mixing room using a color mixing room or by mixing the primary color resin with the color masterbatch Coloring In the past, end-product manufacturers and processors, such as injection molding shop processors, had the experience of encountering some coloring problems when using batch-type latex ABS resins including: 1) Color inconsistencies, even between the same brand of products, different batches of resin underglaze is also very different; 2) different primary colors of ABS resin with different yellow shades. So, whether the end product manufacturers from the same resin manufacturer to take The availability of different grades of ABS resin or the acquisition of ABS resins from different manufacturers require additional operations that involve additional resources and costs.
Figure 1. Particle color: bulk polymerization ABS (left) and emulsion ABS (right)
For end-product manufacturers using primary resin blends with masterbatches, it is generally necessary to frequently use a large amount of pigment to mask the yellowish background of ABS resins from different batches or grades. In addition, ABS moldings Thermal stability and light stability of the parts are also of concern to end-product manufacturers.Because ABS terminal applications are very rich, to improve the coloring efficiency of ABS resin has become particularly important, so this article will explore the light stability of several ABS resins and Thermal stability, end manufacturers to provide reference for them to choose the most suitable products for the ABS material, especially the production of light-colored parts.
First, the primer
At present, ABS resin is generally produced by two different manufacturing processes: Bulk Continuous Polymerization and Batch Emulsion, which are commonly referred to in the industry as Emulsion ABS (eABS) and Bulk ABS (mABS) Compared to the process, using bulk continuous production of ABS resin has many advantages.Therefore, this experiment by bulk polymerization of ABS resin (in this experiment are the trillion MAGNUM ABS, for example, referred to as mABS1) and batch emulsion ABS resin (the experiment using the market-style batch emulsion ABS) performance comparison to explore the advantages of bulk polymerization ABS resin preparation.
Figure 2. Primary ABS resin exposure to QUV-A test results of time and color change
Second, the color characteristics of more
In the batch emulsion process, a grafted rubber concentrate is produced by using butadiene, styrene, acrylonitrile, an emulsifier and a salt, which is then mixed with a styrene acrylonitrile (SAN) resin to prepare an ABS resin. In the process, not all emulsifiers or salts can be removed, some of them will remain in the primary emulsion ABS resin as an impurity, resulting in a yellowish resin ground color due to the different content of impurities in the resin, resulting in the primary colors However, in the bulk polymerization process, polybutadiene rubber, styrene and acrylonitrile are used for polymerization. Since no emulsifier or salt is used in the production process, the color of the produced primary color ABS resin white background, and uniform color.
Figure 3. Color change of ABS primary color forming plate with exposure time in QUV-A test
Figure 1 is a comparison of the background color of bulk polymerized ABS resin with batch emulsion ABS resin, where the ABS resin prepared by bulk polymerization on the left is clearly whiter, which simplifies color matching, especially at the end of the product Needs to be light colored.
◆ UV resin ABS color stability
Absence of pigment dyed ABS resin discoloration occurs when exposed to UV light Color change is mainly reflected in the yellow enhancement, as shown by the b * value (ABS resin yellowing value) increased, the change is due to ABS In the polybutadiene rubber and styrene acrylonitrile (SAN) components are subject to photooxidation, and photooxidation will affect the gloss of molded parts.Figure 2 shows the two primary colors ABS resin (mABS1 and eABS1) after QUV -A color change results after weatherability test It can be seen that since mABS1 is more white background than eABS1, after about 48 hours of QUV-A exposure (equivalent to about 8 months of outdoor exposure), its b * The values reached only the raw b * values of the unexposed eABS 1. The actual color change of the primary color forming panels is shown in Figure 3. The gloss retention is another of the ABS resins except for the color stability in the QUV-A test Key Requirements Figure 4 shows that the mABS1 primary color plate still has a lower gloss retention than the eABS 1 plate after 96 hours of exposure to the QUV-A test.
Figure 4. QUV-A test - primary ABS resin gloss retention and exposure time
◆ primary color ABS resin thermal stability
Parts or end products made of ABS resin may be stored for extended periods of time in high temperature environments (such as container ships shipped across regions or countries) and the color of the product may be discolored by thermal degradation.Thus, the experiment was conducted An aging test simulating high temperature storage and shipping was carried out and the forming plate was placed in an oven maintained at 70 ° C. for 4 weeks .. Oven aging tests were performed on the molded plates of the primary colors mABS1 and eABS1 and the results are shown in Figure 5. It can be seen that after 4 weeks of exposure, Primary color mABS1 shows significantly better thermal stability and less color transition than eABS1, as seen by delta E * = '(delta L *) 2 + (delta a *) 2 + (delta b *) 2' 1/2 Spotted.
Figure 5. Color ABS resin changes over time in oven weathering tests
Third, product color comparison
With a natural white background, bulk polymerization ABS resin is well suited for use in color-challenging products such as bright white and green products Figure 6 shows mABS1 and emulsion ABS molded swatches, both containing 1 % White masterbatch, but the mABS1 swatch on the right is significantly brighter and whiter.
Figure 6. ABS swatch with 1% white masterbatch
The two washing machine door kits are shown in Figure 7. The photo on the right is made from bulk ABS (mABS1) and is brighter and greener than the left-hand side latex ABS (eABS).
Figure 7. ABS resin-formed washer door kit with 3% green masterbatch
Fourth, compare the amount of paint
With a cleaner white background, ABS resins prepared by the bulk polymerization process save pigment costs for end-product manufacturers as well as achieve the production of bright and light-colored products.In Table 1, white and special UV white are used as two For each color, mABS1 was compared to the emulsion-based ABS (eABS 1 or eABS2) swatches colored by the pigmented chamber, mABS1 was the same in all cases as the emulsion ABS with less pigment Color, cost savings of about 40 US dollars / metric ton.
Fifth, the color stability comparison
Results of the light-stable QUV-A or QUV-B tests on ABS resin swatches are shown in Table 1. The results are shown in Figures 8 and 9. For ABS resins, the addition of TiO2 can improve light stability under UV light irradiation The higher the TiO2 content, the better the light stability under UV irradiation. In the QUV-A test (Fig. 8), 2.4% TiO2 mABS1 was added with a delta E * % EABS1 for TiO2 was less. After 50 hours of exposure, the Delta E * value of eABS1 reached 2; in contrast, mABS1 required 90 hours of exposure to achieve the same delta E * level, demonstrating that even with the lower amount of TiO2, mABS1 still has better light stability than eABS1 and can save a color cost of US $ 40 / mt In the QUB-B test (Figure 9), even with less pigment used, the color change of the mABS1 sample (delta For example, mABS1 takes as long as 24 hours (equivalent to 6 months of outdoor exposure) and the delta E * value reaches 3. If end-product manufacturers require a delta E * Is 96 hours The upper limit of delta E * after QUV-B exposure is 3, then 2 ABS samples also need to add UV Stabilizers to meet the requirements.From the photostability results of Figure 9, it can be expected that eABS2 will require more UV stabilizer than mABS1, which will increase raw material costs.
Table 1. Pigment Used and Cost Savings with mABS1
Six, more lasting gloss
UV radiation affects ABS as well as rubber particles and SAN particles Figure 10 is an electron micrograph (SEM) photograph showing the effect of ABS on rubber particles in ABS exposed to UV A left-hand photograph shows the effect of pre-exposure Of the rubber particles and the SAN layer, the dark gray barrier is a rubber particle with the light gray layer in between. The photo to the right shows the situation after exposure to UV and at about 20 microns below the surface, the rubber particles are observed in a SEM The picture is almost invisible because the rubber particles cross-link after UV exposure, almost all double covalent bonds are lost and the formation of a yellow body leads to discoloration of ABS In addition, photodegradation of the SAN layer also causes a yellow body to further Formation of chain breaks in SAN polymers led to a decrease in the molecular weight of the SAN, which further reduced the gloss of the surface.
Figure 8. Pure white resin QUV-A test
One of the most important tests in UV stability testing of ABS resins is to see how well their gloss is maintained.The pure white ABS resin has its gloss retention after exposure to QUV-A as shown in Figure 11. After passing After 96 hours of QUV-A exposure (equivalent to about 16 months of outdoor exposure), mABS1 (with the addition of small amounts of TiO2) showed a gloss retention of 10% above that of eABS1, clearly demonstrating its superior gloss retention.
Figure 9. Special UV white resin QUV-B test
Seven higher thermal stability
In order to simulate long-term storage of parts or end products in high temperature environments, mABS1 and eABS1 resins were made into plain white plates and placed in a constant temperature oven at 70 ° C. for 4 weeks.The color shift is shown in Figure 12. From delta E * It can be seen that mABS1 has little color shift after 4 weeks of storage, demonstrating that it has better thermal stability than eABS 1. This is in good color stability with the previous pair (uncolored) mABS1 at elevated temperatures The test results are consistent.
Figure 10. SEM photo shows the photo-degradation of ABS after exposure to UV light
Eight UV stability comparison
End products such as air conditioners and outdoor equipment need to be exposed to sunlight, so manufacturers have strict requirements on color stability, and they all add UV stabilizers (UV absorbers or UV blocking additives) to their ABS. To compare mABS1, eABS1 and eABS2 three kinds of pure white ABS resin color stability, the experiment by adding these three kinds of ABS in different parts of the UV absorber for comparison.As TiO2 has the effect of improving light stability, so in the weatherability test , 1.5% TiO2 was added to each ABS to highlight the test results.The three ABS materials were added to two common UV absorbers in the same amount, added in three different portions (0.1%, 0.2% and 0.4% ) The primary resin, pigment and UV absorber were compounded into plain white ABS resin swatches for xenon arc and QUV-A testing to assess their light stability.
Figure 11. QUV-A Test - Gloss retention of pure white ABS resin
Figure 12. Color shift of pure white ABS resin over time in an oven weathering test
Figure 13 illustrates the color change of ABS exposed to UV absorbers for 300 hours in the xenon arc test, from which it can be seen that in each ABS, the delta E * increases as the amount of UV absorber increases Will decrease, indicating that the use of UV absorbers can effectively improve the light stability of ABS, but in the test, the degree of color change of the three kinds of ABS resin vary.To meet the specific color requirements, that is, 300 hours after exposure delta E * Value of 2, mABS1 0.1% UV absorber added; eABS1 and eABS2 you need to add 0.4% UV absorber in order to achieve the same effect using a higher amount of UV absorber will be the end product Manufacturers incur the additional cost of producing about 20-35 dollars per 0.1% increase in UV absorber, depending on the UV absorber used, in this example, in order to reach delta E * For the 2 requirement, the cost of adding UV absorbers to eABS1 and eABS2 will be about $ 60-100 / mt higher than mABS1.
Figure 13. Normal White ABS Resins The color change that occurs in a 300 hour xenon arc test after adding different parts of UV absorber
The effect of UV absorbers on the change in ABS color after 96 hours of exposure in the QUV-A test is shown in Figure 14. In order to achieve a specific color change requirement, delta E * of 2 after 96 hours of exposure, mABS1 A 0.4% UV absorber was required, while delta E * for eABS1 and eABS2 far exceeded the value of 2 with the same addition of 0.4% UV absorber, indicating that eABS1 and eABS2 require more UV absorber In order to meet the same requirements, once again show that this will bring significant cost increases for end-product manufacturers.
Figure 14 Color Changes Occurred in the 96 Hour QUV-A Test with Normal White ABS Shaped Plates with Different Amounts of UV Absorbers
Figures 16 and 17 show the gloss retention of the moldings with 0.4% UV absorbers, respectively, under xenon arc and QUV-A tests.The data show that MAGNUM ™ A136 is significantly better gloss retention than the other two emulsion ABSs performance.
Figure 15. The photograph shows the color change of a normal white ABS swatch exposed to QUV-A 96 hours after the addition of different UV absorbers
Figure 16. Xenon Arc Test - Gloss retention of plain white ABS resin after addition of 0.4% UV absorber
Nine conclusions
The results of the study clearly show that the mABS1 resin produced by the bulk polymerization process has the following advantages over the eABS resin produced by the batch emulsion process:
◆ white background helps to face coloring challenges, such as whiter and brighter colors;
◆ using bulk polymerization method ABS resin stained in light colors, can save costs;
◆ primary color and white ABS resin weathering resistance test, even if the pigment is used in small quantities, still maintain good gloss and color stability;
◆ bulk polymerization method ABS resin Pigment use less, the primary color and white resin are still able to maintain excellent thermal stability;
◆ using bulk polymerization ABS For applications that require excellent color stability, UV stabilizers can significantly save the cost.
Figure 17. QUV-A test - gloss retention of plain white ABS resin with 0.4% UV absorber
Bulk Polymerization ABS has significant advantages over emulsion ABS, especially in the search for the best color performance and stability.Abopolymer method The whiteness of the ABS gives it a significant cost-effectiveness when producing a whiter, brighter tone, And can significantly reduce the yellow.Even exposed to ultraviolet light, still maintain the color stability, UV stabilizer can reduce the cost while still maintaining luster.At the same time, the bulk polymerization method ABS can also withstand prolonged high temperature environment, improve storage And transportation efficiency.Therefore, the choice of bulk polymerization ABS can provide customers with consistent color and excellent aesthetic results, with excellent product efficiency and cost savings.