High-whiteness PVC (polyvinyl chloride) composition as well as preparation method and application thereof

Abstract

The invention relates to a high-whiteness PVC (polyvinyl chloride) composition as well as a preparation method and application thereof, and belongs to the technical field of compositions of high-molecular compounds. The high-whiteness PVC composition disclosed by the invention is prepared from the following components in parts by weight: 100 parts of PVC resin, 5 to 10 parts of a toughening agent, 2 to 4 parts of methyltin mercaptide, 0.1 to 0.5 part of maleate, 0.6 to 2 parts of an ester lubricant and 0.6 to 2 parts of an antioxidant. The PVC composition has the advantages of favorable heat resistance and high whiteness at the same time.

Description

Technical Field

[0001] The invention relates to the technical field of polymer compound compositions, and in particular to a high-whiteness PVC composition and a preparation method and application thereof. Background Art

[0002] Polyvinyl chloride (PVC) is a polymer formed by the polymerization of vinyl chloride monomers. Due to its excellent properties such as light weight, high strength, insulation, flame retardancy, and corrosion resistance, it is widely used in building materials, automotive parts, medical devices, packaging materials, etc. However, since PVC molecules contain unstable structures such as tertiary chlorine and allyl chloride, and the terminator remaining in the polymerization process also contains unstable structures, these unstable structures are easily decomposed under thermal conditions, resulting in a decrease in the whiteness of PVC. In addition, the residual initiator in PVC is also easy to decompose to generate free radicals that attack the PVC molecular chain, which in turn causes the PVC to turn yellow and discolor.

[0003] At present, the whiteness of PVC is improved mainly by improving thermal stability, physical modification after polymerization and improving particle size distribution, among which improving thermal stability is the main way to improve the whiteness of PVC. For example, maleic anhydride reacts with the conjugated polyene chain in the PVC molecular chain to undergo Diels-Alder addition reaction, thereby effectively inhibiting the growth of conjugated bonds to inhibit and alleviate its coloration. Alternatively, polyols and metal chlorides are used to absorb HCl generated by the degradation of PVC molecular chains to inhibit the initial coloring performance of PVC. However, these methods of improving the whiteness of PVC by improving thermal stability have limited effect on improving whiteness and it is difficult to effectively improve the initial color stability of the PVC composition. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a high-whiteness PVC composition and a preparation method and application thereof.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] In a first aspect, the present invention provides a high whiteness PVC composition, comprising the following components in parts by weight:

[0007] 100 parts of PVC resin, 5-10 parts of toughening agent, 2-4 parts of methyl tin mercaptan, 0.1-0.5 parts of maleate, 0.6-2 parts of ester lubricant, and 0.6-2 parts of antioxidant.

[0008] The invention combines methyl tin mercaptan, maleate and ester lubricant, takes methyl tin mercaptan as a nucleophilic reagent, utilizes the negatively charged S atom of the methyl tin mercaptan to replace unstable allyl chloride or tertiary chloride in PVC, and simultaneously combines the carbon-carbon double bond in the maleate with the conjugated double bond in the PVC to generate a ring reaction to destroy the growth of the polyene sequence, thereby improving the whiteness of the PVC; and the maleate has good compatibility with PVC, can also play a role in reducing the friction between molecules, and is combined with the dual lubricating effects of internal lubrication and external lubrication of the ester lubricant, so as to effectively reduce the melt temperature to improve the whiteness of the PVC, thereby improving the initial color stability of the PVC composition.

[0009] Optionally, the weight proportion of the toughener in the high whiteness PVC composition can be 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9; the weight proportion of methyl tin mercaptide can be 2.2, 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.4, 3.6, 3.8; the weight proportion of maleate can be 0.2, 0.3, 0.4; the weight proportion of ester lubricant can be 0.8, 1, 1.2, 1.4, 1.6, 1.8; the weight proportion of antioxidant can be 0.8, 1, 1.2, 1.4, 1.6, 1.8. The weight proportion of PVC resin in the composition is not less than 70%.

[0010] As a preferred embodiment of the high whiteness PVC composition of the present invention, the methyl tin mercaptan includes (CH3)3Sn2(SCH2COOC8H 17 )5、(CH3)2Sn(SCH2COOC8H 17 )2. CH3Sn(SCH2COOC8H 17 ) at least one of 3.

[0011] As a preferred embodiment of the high whiteness PVC composition of the present invention, the maleate includes at least one of diethyl maleate, dibutyl maleate and dioctyl maleate.

[0012] As a preferred embodiment of the high whiteness PVC composition of the present invention, the ester lubricant includes at least one of palmityl stearate and pentaerythritol stearate.

[0013] As a preferred embodiment of the high whiteness PVC composition of the present invention, the average degree of polymerization of the PVC resin is ≥400, preferably 500-800, specifically 350, 450, 500, 600, 700, 800. The average degree of polymerization of the PVC resin can be determined using GB / T 5761-2018. As the average degree of polymerization of the PVC resin increases, it is beneficial to improve the whiteness and heat resistance of the PVC composition, but it will also reduce its melt flow and make it difficult to be molded by injection molding.

[0014] As a preferred embodiment of the high whiteness PVC composition of the present invention, the toughening agent includes a core-shell toughening agent, chlorinated polyethylene, preferably an acrylic toughening agent, specifically including at least one of methyl methacrylate-butadiene-styrene copolymer and acrylonitrile-butyl acrylate-styrene.

[0015] As a preferred embodiment of the high whiteness PVC composition of the present invention, the antioxidant at least includes a polyhydric hindered phenol antioxidant and a phosphite antioxidant.

[0016] In a second aspect, the present invention provides a method for preparing the above-mentioned high-whiteness PVC composition, comprising the following steps: mixing the components uniformly and then melt-extruding to obtain the high-whiteness PVC composition.

[0017] Optionally, the melt extrusion in the above preparation method can be carried out using a twin-screw extruder, with the melt extrusion temperature being 100 to 165° C. and the screw speed being 100 to 200 rpm.

[0018] In a third aspect, the present invention provides the use of the high-whiteness PVC composition in the preparation of a battery housing, an electrical appliance housing, an industrial control box or a circuit control box.

[0019] In a fourth aspect, the present invention provides an electrical appliance housing, which is mainly made of the above-mentioned high-whiteness PVC composition.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The invention combines methyl tin mercaptan, maleate and ester lubricant, takes methyl tin mercaptan as a nucleophilic reagent, utilizes the negatively charged S atom of the methyl tin mercaptan to replace unstable allyl chloride or tertiary chloride in PVC, and simultaneously combines the carbon-carbon double bond in the maleate with the conjugated double bond in the PVC to generate a ring reaction to destroy the growth of the polyene sequence, thereby improving the whiteness of the PVC; and the maleate has good compatibility with PVC, can also play a role in reducing the friction between molecules, and is combined with the dual lubricating effects of internal lubrication and external lubrication of the ester lubricant, so as to effectively reduce the melt temperature to improve the whiteness of the PVC, thereby improving the initial color stability of the PVC composition. DETAILED DESCRIPTION

[0022] 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.

[0023] Unless otherwise specified, other materials, reagents, etc. used in the examples and comparative examples can be obtained from commercial sources.

[0024] 1. Raw materials and reagents

[0025] PVC resin 1, average degree of polymerization is 500, brand is PVC S-50, manufacturer is Formosa Plastics Corporation;

[0026] PVC resin 2, average degree of polymerization is 400, brand is PVC JLTS-1, manufacturer is Sichuan Jinlu Resin Co., Ltd.;

[0027] PVC resin 3, average degree of polymerization is 800, brand is PVC TL-800, manufacturer is Tianjin LG Bohai Chemical Co., Ltd.;

[0028] Toughener 1 (acrylate), brand name PARALOID KM-355P, manufacturer: Rohm and Haas Chemical Co., Ltd.;

[0029] Toughener 2 (MBS type), brand name Kane Ace B-564, manufacturer: Kane Ace of Japan;

[0030] Maleate 1 (dibutyl maleate), brand name dibutyl maleate, manufacturer is Hunan Zhenyuan Chemical;

[0031] Maleate 2 (dioctyl maleate), brand name is dioctyl maleate, manufacturer is Hubei Jusheng Technology;

[0032] Ester lubricant 1 (palmityl stearate), brand name LOXIOL G32, manufacturer: Emory Oleochemical;

[0033] Ester lubricant 2 (tetrastearyl pentaerythritol ester), brand name LOXIOL P861 / 3.5, manufacturer: Emery Oleochemical;

[0034] Methyltin mercaptan, brand name YT-181, manufacturer: Yunnan Tin Industry Group Co., Ltd.

[0035] Maleic acid organotin, brand DX-650, manufacturer is Quzhou Jianhua Dongxu Additives Co., Ltd.;

[0036] The stearate lubricant is calcium stearate, the primary antioxidant is antioxidant 1010, and the secondary antioxidants are antioxidant 627A and maleic anhydride, all of which are commercially available.

[0037] 2. Examples 1 to 8 and Comparative Examples 1 to 5

[0038] Table 1 Weight percentage of each component of high whiteness PVC composition in Examples 1 to 8

[0039] Example 1 2 3 4 5 6 7 8 PVC resin 1 100 / / 100 100 100 100 100 PVC resin 2 / 100 / / / / / / PVC resin 3 / / 100 / / / / / Toughener 1 8 8 8 / 8 8 5 10 Toughener 2 / / / 8 / / / / Methyltin mercaptan 3 3 3 3 3 3 4 2 Maleate 1 0.3 0.3 0.3 0.3 / 0.3 0.1 0.5 Maleate 2 / / / / 0.3 / / / Ester lubricant1 0.8 0.8 0.8 0.8 0.8 / 2 0.6 Ester lubricant 2 / / / / / 0.8 / / Primary Antioxidant 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 Secondary antioxidant 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2

[0040] The method for preparing the high whiteness PVC composition comprises the following steps:

[0041] According to the formula, PVC resin, toughening agent, methyl tin mercaptan, maleate, antioxidant and ester lubricant are uniformly mixed, added into a twin-screw extruder for melt extrusion, and a high-whiteness PVC composition is obtained;

[0042] Among them, the temperature zones of the twin-screw extruder are set as follows: zone 1 is 100°C, zone 2 is 150°C, zone 3 is 165°C, zone 4 is 165°C, zone 5 is 165°C, zone 6 is 165°C, zone 7 is 165°C, zone 8 is 165°C, and zone 9 is 160°C; the screw speed is 150rpm, and the screw aspect ratio is 40:1.

[0043] Table 2 Weight percentage of each component of high whiteness PVC composition in Comparative Examples 1 to 5

[0044] Comparative Example 1 2 3 4 5 PVC resin 1 100 100 100 100 100 Toughener 1 8 8 8 8 8 Methyltin mercaptan / 3 3 3 / Methyltin maleate 3 / / / / Maleate 1 0.3 / 0.3 / 0.3 Maleic anhydride / 0.3 / / / Ester lubricant1 0.8 0.8 / 0.8 0.8 Calcium stearate / / 0.8 / / Primary Antioxidant 0.4 0.4 0.4 0.4 0.4 Secondary antioxidant 0.2 0.2 0.2 0.2 0.2

[0045] The method for preparing the high whiteness PVC composition comprises the following steps:

[0046] According to the formula, PVC resin, toughening agent, methyl tin mercaptan, maleate, antioxidant and ester lubricant are uniformly mixed, added into a twin-screw extruder for melt extrusion, and a high-whiteness PVC composition is obtained;

[0047] Among them, the temperature zones of the twin-screw extruder are set as follows: zone 1 is 100°C, zone 2 is 150°C, zone 3 is 165°C, zone 4 is 165°C, zone 5 is 165°C, zone 6 is 165°C, zone 7 is 165°C, zone 8 is 165°C, and zone 9 is 160°C; the screw speed is 150rpm, and the screw aspect ratio is 40:1.

[0048] 3. Performance testing

[0049] 1) b value: After the sample to be tested is injection molded into a color plate, its b value is tested using a colorimeter.

[0050] 2) Vicat softening point: in accordance with standard GB / T 1633-2000B 120 The test is carried out in accordance with the Determination of Vicat Softening Temperature (VST) of Thermoplastics.

[0051] Table 3 Properties of high whiteness PVC compositions in various examples and comparative examples

[0052]

[0053]

[0054] According to the data in Table 3, the Vicat softening point of the high whiteness PVC composition in Examples 1 to 8 is maintained at ≥74°C, and the b value is less than or equal to 1.3, indicating that the PVC composition of the present invention not only maintains good heat resistance, but also has high whiteness (initial color stability). In addition, according to Example 1, Comparative Example 1 and Comparative Example 5, it can be seen that compared with the combination of maleic acid ester and ester lubricant, although methyl tin maleate can improve the whiteness of the PVC composition to a certain extent after being combined with the two, the improvement effect is limited; at the same time, combined with Comparative Examples 2 and 3, it is further explained that replacing maleic acid ester with maleic anhydride, or replacing ester lubricant with calcium stearate, can make the PVC composition have good heat resistance, but cannot significantly improve its whiteness, indicating that the combination of methyl tin mercaptide, maleic acid ester and ester lubricant has a synergistic effect.

[0055] 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 high whiteness PVC composition, characterized in that: The invention comprises the following components by weight: 100 parts of PVC resin, 5-10 parts of toughening agent, 2-4 parts of methyl tin mercaptide, 0.1-0.5 parts of maleic acid ester, 0.6-2 parts of ester lubricant and 0.6-2 parts of antioxidant.

2. The high whiteness PVC composition according to claim 1, characterized in that: The maleate includes at least one of diethyl maleate, dibutyl maleate and dioctyl maleate.

3. The high whiteness PVC composition according to claim 1, characterized in that: The ester lubricant includes at least one of palmityl stearate and pentaerythritol stearate.

4. The high whiteness PVC composition according to claim 1, characterized in that: The average polymerization degree of the PVC resin is ≥400.

5. The high whiteness PVC composition according to claim 4, characterized in that: The average polymerization degree of the PVC resin is 500-800.

6. The high whiteness PVC composition according to claim 1, characterized in that: The toughening agent includes at least one of methyl methacrylate-butadiene-styrene copolymer, acrylonitrile-butyl acrylate-styrene copolymer and chlorinated polyethylene.

7. The high whiteness PVC composition according to any one of claims 1 to 6, characterized in that: The antioxidant at least includes a polyhedral hindered phenol antioxidant and a phosphite antioxidant.

8. The method for preparing the high whiteness PVC composition according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: mixing the components uniformly and then melting and extruding them to obtain a high-whiteness PVC composition.

9. Use of the high whiteness PVC composition according to any one of claims 1 to 7 in the preparation of battery housings, electrical appliance housings, industrial control boxes or circuit control boxes.

10. An electrical appliance housing, characterized in that: The electrical appliance housing is mainly made of the high-whiteness PVC composition described in any one of claims 1 to 7.

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