A shear stress color-changing PMMA material and its preparation method and application

Abstract

The present invention develops a shear stress color-changing PMMA material and its preparation method and application, which belongs to the technical field of engineering plastics. The shear stress color-changing PMMA material comprises the following components in parts by weight: 100 parts of PMMA resin, 25 to 60 parts of tackifying particles, and 0.2 to 2.5 parts of isoindolinone yellow pigment. The shear stress color-changing PMMA material of the present invention uses PMMA resin as a matrix, and also includes tackifying particles and isoindolinone yellow pigment. The material can change color when subjected to shear stress, thereby realizing accurate detection of PMMA shear stress resistance performance.

Description

Technical Field

[0001] The invention relates to the technical field of engineering plastics, in particular to a shear stress color-changing PMMA material and a preparation method and application thereof. Background Art

[0002] When plastics are injected at high speed, shear stress has a great influence on the performance of plastic parts. Plastic parts may warp, lose strength, and have appearance defects under large shear stress. The shear stress resistance of plastics is complex and related to many factors. In addition to the injection molding conditions, the molecular structure, melt strength, melt flow rate, crystallinity, viscosity and other related parameters of the plastic itself will affect its shear stress resistance. Therefore, studying whether plastics have good shear stress resistance is a relatively comprehensive and complex topic.

[0003] In recent years, simulation has played a good theoretical guiding role in the opening of injection molds. By simulating the high-speed filling of plastics into molds, the shear stress resistance of plastics can be simulated to a certain extent. The distribution of shear stress can be displayed by computer simulation imaging, so as to optimize the shear stress during mold forming when the injection molded parts are opened. However, simulation also has certain defects: (1) Before simulation, it is necessary to accurately master the material properties of the injection molding material rheology in advance to effectively simulate the mold shear stress; (2) There are differences between the calculation formulas and mathematical models used in simulation and the actual injection molding situation, and they cannot be completely matched; (3) Simulation requires the establishment of different simulation models for each mold and injection molding material, which is time-consuming and cumbersome. Therefore, the use of simulation methods to study the shear stress resistance of plastics is not only difficult to apply to large-scale industrial production, but more importantly, the simulation method still has certain errors. It can often only detect larger shear stresses, and due to the errors, it cannot simulate lighter shear stresses, making it difficult to accurately predict the appearance defects of actual injection molding.

[0004] PMMA material is a thermoplastic plastic, and PMMA parts are usually prepared by injection molding. Appearance defects often occur under the action of shear stress during injection molding. Therefore, it is necessary to provide a material or method that can accurately detect the shear stress resistance of PMMA. Summary of the invention

[0005] The purpose of the present invention is to overcome the defect that the shear stress resistance performance cannot be accurately detected in the prior art, and to provide a shear stress color-changing PMMA material, which takes PMMA resin as a matrix and also includes viscosity-increasing particles and isoindolinone yellow pigments. The material can change color when subjected to shear stress, thereby realizing accurate detection of the shear stress resistance performance of PMMA.

[0006] Another object of the present invention is to provide a method for preparing the above-mentioned shear stress color-changing PMMA material.

[0007] Another object of the present invention is to provide an application of the above-mentioned shear stress color-changing PMMA material in testing the shear stress resistance performance of PMMA resin.

[0008] To achieve the above object, the present invention adopts the following technical solution:

[0009] A shear stress color-changing PMMA material, comprising the following components in parts by weight:

[0010] 100 parts of PMMA resin,

[0011] 25-60 parts of thickening particles,

[0012] Isoindolinone yellow pigment 0.2-2.5 parts.

[0013] The shear stress color-changing PMMA material of the present invention uses PMMA resin as a matrix and further comprises viscosity-increasing particles and isoindolinone yellow pigments. The shear stress color-changing PMMA material can change color when subjected to shear stress.

[0014] Isoindolinone yellow pigment is an organic yellow pigment, and the shear stress color-changing PMMA material prepared by adding it to the PMMA matrix is ​​a yellow appearance material. Isoindolinone yellow pigment contains carbonyl, imino, cyano and amide functional groups, and has a large number of hydrogen bonds between molecules and within molecules. The inventor unexpectedly found that when isoindolinone yellow pigment is added to the PMMA system of the present invention, the material will cause the intermolecular hydrogen bonds to break during high-speed injection molding due to the strong shear force, thereby causing the overall color spectrum of the material to blue shift, showing a more obvious yellow fading appearance change phenomenon. Preferably, the isoindolinone yellow pigment is a chloroisoindolinone yellow pigment.

[0015] The viscosity-increasing particles play a viscosity-increasing role in the PMMA system of the present invention, which helps to amplify the tolerance of the PMMA resin to shear stress, thereby more accurately capturing the influence of weak shear stress on the PMMA resin.

[0016] Preferably, the isoindolinone yellow pigment is at least one of Pigment Yellow 110, Pigment Yellow 109 and Pigment Yellow 139.

[0017] Pigment Yellow 110, molecular formula is C 22 H6Cl8N4O2, CAS number is 5590-18-1; Pigment Yellow 109, molecular formula is C 23 H8Cl8N4O2, CAS number is 5045-40-9; Pigment Yellow 139, molecular formula is C16 H9N5O6, CAS number is 36888-99-0.

[0018] More preferably, the isoindolinone yellow pigment is Pigment Yellow 110 and / or Pigment Yellow 109.

[0019] More preferably, the isoindolinone yellow pigment is Pigment Yellow 110.

[0020] Pigment Yellow 110 is a yellow organic pigment with very strong red light. After being added to the PMMA / thickening particle system of the present invention, the original red-yellow light turns blue more obviously after shearing force, making it easier to capture the effect of weak shear stress on PMMA resin.

[0021] Preferably, the average particle size of the viscosity-enhancing particles is 150 to 300 nm.

[0022] For the PMMA material of the present invention, the particle size of the tackifying particles should not be too large or too small. When the average particle size of the tackifying particles is too large, the light transmittance of the shear stress color-changing PMMA material will be affected, so that the color change effect of the material under the shear stress is not obvious. When the average particle size of the tackifying particles is too small, the tackifying effect on PMMA is limited, which will affect the detection effect.

[0023] More preferably, the average particle size of the viscosity-increasing particles is 180 to 220 nm.

[0024] It should be noted that the particle size of the tackifying particles in the present invention refers to the particle size of the entire tackifying particles, and in particular, for tackifying particles with a core-shell structure, the particle size of the tackifying particles refers to the overall particle size of the shell and core structure. The average particle size of the tackifying particles can be obtained by laser particle size analyzer and transmission electron microscope.

[0025] Preferably, the refractive index of the tackifying particles is 1.49 to 1.5. More preferably, the refractive index of the tackifying particles is 1.49.

[0026] It should be noted that the refractive index of the thickening particles in the present invention refers to the refractive index of the entire thickening particles. In particular, for thickening particles having a core-shell structure, the refractive index of the thickening particles refers to the refractive index of the entire shell and core structure.

[0027] Preferably, the viscosity-increasing particles are rubber with a core-shell structure, wherein the core is a copolymer of styrene and acrylate, and the shell is polymethyl methacrylate.

[0028] The shell layer of the viscosity-enhancing particles has good compatibility with the matrix resin PMMA, which strengthens the interfacial bonding and volume-enhancing effect. The core of the viscosity-enhancing particles can be deformed under the action of external force and processing shear, causing silver streaks to turn white.

[0029] For the thickening particles with a core-shell structure, the refractive index is affected by the ratio of the copolymer monomers of styrene and acrylate copolymers, and the refractive index of the thickening particles can be controlled by adjusting the ratio of the copolymer monomers of styrene and acrylate, so that the refractive index of the thickening particles is 1.49 to 1.5. The refractive index of the thickening particles is 1.49 to 1.5, especially when the refractive index is 1.49, which is close to the refractive index of PMMA, and the addition of thickening particles will not affect the light transmission performance of the PMMA material.

[0030] Preferably, the viscosity-increasing particles are copolymerized methyl methacrylate-butyl acrylate-styrene (MBS) core-shell rubber.

[0031] Preferably, the shear stress color-changing PMMA material comprises the following components in parts by weight:

[0032] 100 parts of PMMA resin,

[0033] Thickening particles 30-50 parts,

[0034] 1 to 2 parts of isoindolinone yellow pigment.

[0035] For the shear stress color-changing PMMA material of the present invention, the addition amount of thickening particles and isoindolinone yellow pigment will comprehensively affect the shear stress color-changing effect of the material. When the content of thickening particles is high, the viscosity of the PMMA material is high and it is easy to turn white, which affects the accurate detection of shear stress performance; when the content of thickening particles is low, the thickening effect on PMMA is limited, which in turn affects the detection effect; when the content of isoindolinone yellow pigment is too much, the material itself is too dark yellow, and the non-discolored part is easy to cover the discolored part under the action of shear stress, affecting the detection effect; when the content of isoindolinone yellow pigment is too little, the shear color-changing effect is not obvious.

[0036] The inventors have found that when the component content of the shear stress color-changing PMMA material is within the above preferred range, the PMMA material can undergo more obvious color change when subjected to shear stress, thereby enabling accurate detection of the PMMA shear stress resistance performance.

[0037] Preferably, the melt flow rate of the PMMA resin at 230° C. and 2.16 kg is 2 to 8 g / 10 min.

[0038] The melt flow rate of PMMA resin was measured according to ASTM D1238-2010 standard method.

[0039] Preferably, the shear stress color-changing PMMA material may further include 0.1 to 2 parts of an antioxidant and 0.1 to 2 parts of a lubricant.

[0040] Optionally, the antioxidant is a hindered phenol antioxidant and / or a phosphite antioxidant.

[0041] Optionally, the lubricant is at least one of pentaerythritol stearate, erucamide, oleamide, and ethylene bisstearamide.

[0042] The present invention also protects a method for preparing the above-mentioned shear stress color-changing PMMA material, comprising the following steps:

[0043] The PMMA resin, the tackifying particles, the isoindolinone yellow pigment, the antioxidant (if any), and the lubricant (if any) are mixed, and then melt-blended and extruded on a mechanical device to obtain the shear stress color-changing PMMA material.

[0044] Preferably, the processing temperature of the mechanical device is 120-240° C., and the rotation speed is 50-600 rpm.

[0045] Preferably, the mechanical device is a twin-screw extruder.

[0046] Preferably, the temperature of zones 1 to 2 of the twin-screw extruder is 120-190° C., the temperature of zones 3 to 5 is 200-240° C., the temperature of zones 6 to 10 is 200-240° C., and the screw speed is 350-450 rpm.

[0047] The present invention also protects the use of the shear stress color-changing PMMA material in testing the shear stress resistance performance of PMMA resin.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] The present invention develops a shear stress color-changing PMMA material, which takes PMMA resin as a matrix and also includes viscosity-increasing particles and isoindolinone yellow pigments. The material can change color when subjected to shear stress, thereby achieving accurate detection of the shear stress resistance performance of PMMA. DETAILED DESCRIPTION

[0050] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments, but the embodiments do not limit the present invention in any form.

[0051] In the embodiments and comparative examples of the present invention, the sources of raw materials used are as follows:

[0052] PMMA resin:

[0053] PMMA-1, purchased from Chimei manufacturer CM-205, with a melt flow rate of 2g / 10min at 230℃ and 2.16kg;

[0054] PMMA-2, purchased from Rohm, 8N grade, with a melt flow rate of 5 g / 10 min at 230°C and 2.16 kg;

[0055] PMMA-3, purchased from Sumitomo manufacturer LG brand, with a melt flow rate of 8 g / 10 min at 230°C and 2.16 kg;

[0056] Thickening particles 1 to 4, core-shell structure, the core is copolymerized methyl methacrylate-butyl acrylate-styrene (MBS), the shell is polymethyl methacrylate, self-made, and prepared according to the method described in reference (Guo Ruiqiang, Pan Mingwang, Yuan Jinfeng, Meng Qingrong, Zhang Liucheng. Study on preparation of high transmittance toughness PMMA composite resin by in-situ polymerization [J]. China Plastics, 2005 (03): 24-27.) to obtain thickening particles of different particle sizes:

[0057] Thickening particles-1, average particle size 150nm, refractive index 1.49;

[0058] Thickening particles-2, average particle size 180nm, refractive index 1.49;

[0059] Thickening particles-3, average particle size 220nm, refractive index 1.49;

[0060] Thickening particles-4, average particle size 300nm, refractive index 1.49;

[0061] Tackifying particles-5, ASAFLEX 830, styrene-butadiene block copolymer, average particle size of 200 nm, refractive index of 1.57;

[0062] Thickening particles-6, EM500, core-shell structure, the core is copolymerized methyl methacrylate-butadiene-styrene, the shell is polymethyl methacrylate, the average particle size is 200nm, and the refractive index is 1.52;

[0063] Isoindolinone yellow pigments:

[0064] Yellow pigment-1, Pigment Yellow 110, purchased from BASF manufacturer Irgazin Yellow K2060SQ brand;

[0065] Yellow pigment-2, Pigment Yellow 109, purchased from BASF manufacturer Irgazin Yellow L1030 brand;

[0066] Yellow pigment-3, Pigment Yellow 139, purchased from BASF manufacturer Paliotol Yellow L 2146HD brand;

[0067] Other yellow pigments:

[0068] Yellow pigment-4, Pigment Yellow 180, purchased from Clariant manufacturer PV Fast Yellow G180 brand;

[0069] Antioxidant: a mixture of antioxidant 1010 and antioxidant 168 in a weight ratio of 2:1;

[0070] Lubricant: Pentaerythritol stearate.

[0071] Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art. Unless otherwise specified, the reagents and materials used in the present invention are commercially available.

[0072] Examples 1 to 18

[0073] Examples 1 to 18 provide a PMMA material respectively, the component contents are shown in Table 1, and the preparation method is as follows:

[0074] After mixing the components according to Table 1, add them to a twin-screw extruder, the temperature of zones 1 to 2 of the twin-screw extruder is 120-190° C., the temperature of zones 3 to 5 is 200-240° C., the temperature of zones 6 to 10 is 200-240° C., the screw speed is 350-450 rpm, and melt blending and extrusion are performed to obtain PMMA material.

[0075] Table 1

[0076]

[0077]

[0078]

[0079] Comparative Examples 1 to 6

[0080] Comparative Examples 1 to 6 provide a PMMA material respectively, the component contents are shown in Table 2, and the preparation methods are as follows:

[0081] After mixing the components according to Table 2, add them to a twin-screw extruder, the temperature of zones 1 to 2 of the twin-screw extruder is 120-190°C, the temperature of zones 3 to 5 is 200-240°C, the temperature of zones 6 to 10 is 200-240°C, the screw speed is 350-450rpm, and melt blending and extrusion are performed to obtain PMMA material.

[0082] Table 2

[0083]

[0084] Performance Testing

[0085] The performance test of the PMMA materials prepared in the above embodiments and comparative examples is carried out as follows:

[0086] Color difference under high shear force: PMMA materials were injection molded into samples with a specification of 1*100*100mm. The injection speed was 200mm / s and the injection temperature was 220℃. The color b value change (Δb) between the top and the bottom of the sample was tested using a colorimeter according to the CIE 2004SCI D65) method.

[0087] Color difference under low shear force: PMMA materials were injection molded into samples with a specification of 1*100*100mm. The injection speed was 50mm / s and the injection temperature was 220℃. The color b value change (Δb) between the top and the bottom of the sample was tested using a colorimeter according to the CIE 2004SCI D65 method.

[0088] The degree of color difference reflects the color change of PMMA material under shear stress. The larger the color difference, the worse the shear stress resistance of PMMA material.

[0089] The test results of the embodiments are shown in Table 3, and the test results of the comparative examples are shown in Table 4.

[0090] Table 3

[0091]

[0092]

[0093] Table 4

[0094]

[0095] For PMMA injection molding samples, the bottom of the end is prone to discoloration relative to the top, so the color difference Δb between the top and the bottom of the end is selected for detection in the present invention. According to the test results in Table 3, for different PMMA resins, the PMMA material of the present invention can show a large color b value change after injection molding (|Δb|≥1.10 under high shear force, |Δb|≥0.65 under low shear force), indicating that the material can show obvious discoloration under high shear force or low shear force, thereby realizing accurate detection of PMMA shear stress resistance performance.

[0096] According to Examples 1 to 4, different particle sizes of thickening particles have a certain effect on the color change effect of PMMA materials. When the average particle size of the thickening particles is 180 to 220 nm, the thickening particles can not only play a good role in thickening PMMA, but also will not affect its light transmission performance, thereby making the color change of PMMA materials more obvious; according to Examples 1, 5, and 6, when the refractive index of the thickening particles is 1.49, it is close to the refractive index of PMMA, and the detection effect of PMMA shear stress resistance performance is more accurate.

[0097] According to Examples 1, 7, and 8, the color change effect of the PMMA material prepared by using Pigment Yellow 110 as the isoindolinone yellow pigment is more significant, especially the color b value changes more under low shear force. This may be because Pigment Yellow 110 is a yellow organic pigment with strong red light. After shear force, the original red-yellow light changes to a more obvious blue color, making it easier to capture the effect of weak shear stress on PMMA resin.

[0098] According to Example 1 and Examples 11 to 18, when the component contents of the PMMA material are: 100 parts of PMMA resin, 30 to 50 parts of viscosity-enhancing particles, and 1 to 2 parts of isoindolinone yellow pigment, the color-changing effect of the PMMA material is more significant, and |Δb|≥1.70 under high shear force and |Δb|≥1.20 under low shear force.

[0099] Comparative Example 1 is a PMMA material without isoindolinone yellow pigment. Although the thickening particles are added to increase the viscosity of PMMA to a certain extent, the PMMA material has no color and does not contain hydrogen bonds in isoindolinone yellow pigments, so the color spectrum cannot change. Therefore, the color change effect of the PMMA material under shear force is very weak, and it is difficult to detect the shear stress resistance of PMMA.

[0100] Comparative Example 2 uses yellow pigment-4 (Pigment Yellow 180). The CAS number of Pigment Yellow 180 is 77804-81-0, which belongs to azo pigments. Although the PMMA material of Comparative Example 2 contains yellow pigment, that is, the material itself has a yellow appearance effect, the azo pigment cannot significantly blue-shift the color spectrum of isoindolinone yellow pigments under shear force, thereby changing the appearance of the material.

[0101] According to Comparative Examples 3 to 6, it can be seen that when the content of thickening particles or isoindolinone yellow pigments is too little or too much, it will have a certain negative impact on the appearance change of the PMMA material, making the color change effect of the PMMA material not obvious, and unable to achieve accurate detection of the shear stress resistance of PMMA.

[0102] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A shear stress color-changing PMMA material, characterized in that: The composition comprises the following components in parts by weight: 100 parts of PMMA resin, 25~60 parts of thickening particles, 0.2~2.5 parts of isoindolinone yellow pigment, The viscosity-increasing particles are rubber with a core-shell structure, wherein the core is a copolymer of styrene and acrylate, and the shell is polymethyl methacrylate.

2. The shear stress color-changing PMMA material according to claim 1, characterized in that: The isoindolinone yellow pigment is at least one of Pigment Yellow 110, Pigment Yellow 109 and Pigment Yellow 139.

3. The shear stress color-changing PMMA material according to claim 2, characterized in that: The isoindolinone yellow pigment is Pigment Yellow 110.

4. The shear stress color-changing PMMA material according to claim 1, characterized in that: The average particle size of the viscosity-increasing particles is 150-300 nm.

5. The shear stress color-changing PMMA material according to claim 1, characterized in that: The refractive index of the viscosity-enhancing particles is 1.49-1.

5.

6. The shear stress color-changing PMMA material according to claim 1, characterized in that: The composition comprises the following components in parts by weight: 100 parts of PMMA resin, Thickening particles 30~50 parts, 1~2 parts of isoindolinone yellow pigment.

7. The method for preparing the shear stress color-changing PMMA material according to any one of claims 1 to 6, characterized in that: The following steps are involved: The PMMA resin, the viscosity-increasing particles and the isoindolinone yellow pigment are mixed and then melt-blended and extruded on a mechanical device to obtain the shear stress color-changing PMMA material.

8. The preparation method according to claim 7, characterized in that: The mechanical device is a twin-screw extruder, the temperature of the first to second zones of the twin-screw extruder is 120-190°C, the temperature of the third to fifth zones is 200-240°C, the temperature of the sixth to tenth zones is 200-240°C, and the screw speed is 350-450rpm.

9. Use of the shear stress color-changing PMMA material according to any one of claims 1 to 6 in testing the shear stress resistance performance of PMMA resin.

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