A method for producing chlorinated polyethylene grafted with butyl methacrylate

Abstract

The present invention belongs to the technical field of graft modification of chlorinated polyethylene, and discloses a production method of grafting butyl methacrylate on chlorinated polyethylene, comprising the following steps: S1, adding polyethylene and various additives into a reactor containing hydrochloric acid and stirring evenly; S2, controlling the pressure and temperature in the reactor, and introducing a certain amount of chlorine; S3, releasing the pressure after the chlorination reaction is completed, purging the reactor with nitrogen, cooling it to 40-50°C, adding a catalyst and a grafting monomer, and controlling the temperature of the grafting stage to be 40-50°C; S4, centrifuging the material after the grafting reaction is completed, washing it with an organic solvent, and drying it to obtain the product. The method of the present invention has mild reaction conditions and is easy to operate. The fracture strength and elongation at break of the grafted product prepared by the method are significantly improved compared with chlorinated polyethylene, which greatly improves the shortcomings of unstable quality, high monomer loss, and difficult operation of the products prepared by melt grafting and free radical polymerization technology.

Description

Technical Field

[0001] The invention belongs to the technical field of graft modification of chlorinated polyethylene, and in particular relates to a production method of chlorinated polyethylene grafted with butyl methacrylate. Background Art

[0002] Chlorinated polyethylene (CPE) is a saturated polymer material with the appearance of white powder, non-toxic and odorless, with good weather resistance, ozone resistance, chemical resistance and aging resistance. It has good compatibility with other polymer materials, but it is easy to remove HCl when heated, and the molecular chain is easy to decompose under heat, and its breaking strength and elongation at break become worse. Its performance can be improved by grafting other monomers.

[0003] At present, the traditional methods for preparing chlorinated polyethylene chlorine grafts are mainly melt grafting, solution grafting and suspension grafting. Among them, when chlorinated polyethylene is melt grafted with butyl methacrylate, it faces problems such as uneven grafting, insignificant performance improvement, and monomer decomposition; solution grafting is the in-situ polymerization of polyolefins and monomers under chlorine catalysis. In-situ polymerization faces problems such as low grafting rate due to monomer self-polymerization and high cost due to the inability to recycle after separation of self-polymerized monomers; common suspension polymerization methods are divided into free radical polymerization and atom transfer radical polymerization. Traditional free radical polymerization and atom transfer radical polymerization need to be carried out in organic solvents under nitrogen protection. The process steps are cumbersome, the operation is difficult, and the product quality is unstable, which limits the production of chlorinated polyethylene grafts and hinders the expansion of the use of chlorinated polyethylene grafted with butyl methacrylate. It is extremely unfavorable to the application and promotion of chlorinated polyethylene grafts and the improvement of product quality. Summary of the invention

[0004] In view of the shortcomings in the current production process of chlorinated polyethylene grafts, the technical problem to be solved by the present invention is to provide a production method of chlorinated polyethylene grafted with butyl methacrylate. The method has mild reaction conditions and is easy to operate. The breaking strength and breaking elongation of the chlorinated polyethylene graft product prepared by the method are significantly improved compared with those of chlorinated polyethylene, which greatly improves the shortcomings of unstable quality, high monomer loss, and difficult operation of products prepared by melt grafting and free radical polymerization technology.

[0005] In order to solve the above technical problems, the technical solution of the present invention is:

[0006] A method for producing chlorinated polyethylene grafted with butyl methacrylate comprises the following steps:

[0007] S1. Add polyethylene and various additives into a reactor containing hydrochloric acid and stir evenly;

[0008] S2. When the temperature rises to 45-55°C, chlorine gas is introduced into the reactor, and the reaction temperature is controlled to be 100-110°C, the pressure is 0.4-0.5Mpa, and the time is 3-5h;

[0009] S3, after the chlorination reaction is completed, the pressure is released, the reactor is purged with nitrogen, replaced with a nitrogen atmosphere, the temperature is lowered to 40-50°C, a catalyst and a grafting monomer are added, and the temperature of the grafting stage is controlled at 40-50°C for 6-8h;

[0010] S4, centrifuging the material after the grafting reaction, washing with an organic solvent and then drying to obtain chlorinated polyethylene grafted with butyl methacrylate.

[0011] The chlorination and grafting process of polyethylene is shown in the following formula:

[0012]

[0013] Wherein, in step S1, the mass percentage concentration of the hydrochloric acid used is 18% to 22%, preferably 20%.

[0014] In order to increase the dispersibility of polyethylene in hydrochloric acid, a dispersant is added to the hydrochloric acid. The dispersant can be selected from one or a combination of any proportions of sodium methacrylate-2-ethanesulfonate, propylene oxide and ethylene oxide polymer, sodium dodecyl sulfate, nonylphenol polyoxyethylene ether, octylphenol polyoxyethylene ether and a composite emulsifier.

[0015] In order to increase the suspension stability of polyethylene in the hydrochloric acid phase, a suspension stabilizer is added to the hydrochloric acid. The suspension stabilizer can be selected from hydroxyethyl cellulose, polyvinyl alcohol, polyvinyl pyrrolidone, sodium polyacrylate, or a combination of any proportions of the two or more.

[0016] In step S3, the catalyst is an atom transfer radical polymerization catalyst system, and cuprous chloride / bipyridine system, cuprous chloride / o-phenanthroline system, carboxy cuprous / bipyridine system, ruthenium chloride / triphenylphosphine system, ferrous chloride / triphenylphosphine system, cuprous chloride / triphenylphosphine system can be selected, preferably cuprous chloride / triphenylphosphine system, and the weight ratio of central metal to ligand is 1:1.

[0017] Preferably, in step S3, the grafting monomer includes butyl methacrylate and a second monomer, and the mass ratio of the butyl methacrylate to the second monomer is 25-40:5-8. The second monomer is one or a combination of any proportion of acrylic acid, methyl acrylate, ethyl acrylate, glycidyl acrylate, and butyl acrylate. The second monomer is preferably butyl acrylate.

[0018] Preferably, the weight proportions of the raw materials are as follows: chlorination stage: 100 parts of polyethylene, 0.02-0.8 parts of dispersant, 0.02-0.8 parts of suspension stabilizer, 400-700 parts of hydrochloric acid; grafting stage: 10-20 parts of catalyst, 25-40 parts of butyl methacrylate, 5-8 parts of butyl acrylate.

[0019] In step S4, the organic solvent is one of ethanol, ether, methanol, ethyl acetate, and dichloromethane, preferably ethanol.

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

[0021] (1) The present invention directly prepares chlorinated polyethylene grafted with butyl methacrylate by subjecting polyethylene to chlorination reaction and atom transfer radical polymerization reaction. Suspension polymerization grafting is adopted to avoid the uneven grafting distribution phenomenon caused by melt grafting to prepare chlorinated polyethylene grafted with butyl methacrylate, thereby ensuring that the prepared chlorinated polyethylene grafted with butyl methacrylate is grafted uniformly. A chlorinated polyethylene grafted with butyl methacrylate product with a grafting rate of 4.8% to 6.6% can be obtained, and the product quality is stable.

[0022] (2) Due to the use of atom transfer radical polymerization, the technical problem of serious self-polymerization of grafted monomers caused by in-situ polymerization grafting is solved, the monomer recovery is achieved, the monomer waste caused by monomer polymerization in the preparation of grafted compounds by in-situ polymerization is avoided, and the disadvantage of poor uniformity of monomer distribution in the molecular chain during melt grafting is avoided. As a result, the quality of chlorinated polyethylene grafted butyl methacrylate products is greatly improved, and chlorinated polyethylene grafted butyl methacrylate can be used in more fields.

[0023] (3) The present invention can freely control the mass fraction of chlorine in chlorinated polyethylene through a "one-pot" reaction. Through atom transfer radical polymerization, the grafting rate of chlorinated polyethylene grafted with butyl methacrylate can reach 6.6%, thereby enriching the product types and meeting the requirements of a wider range of application fields.

[0024] (4) The method of the present invention has mild reaction conditions and is easy to operate. While reducing the difficulty of operation, it improves the economic efficiency of the production process of chlorinated polyethylene grafted with butyl methacrylate. The breaking strength and breaking elongation of the chlorinated polyethylene grafted product prepared by this method are significantly improved compared with chlorinated polyethylene, and has great market prospects and promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The following drawings are intended only to illustrate and explain the present invention, and are not intended to limit the scope of the present invention.

[0026] Figure 1It is the infrared spectra of the grafted product obtained in Example 1 of the present invention and the chlorinated polyethylene obtained in Comparative Example 1. DETAILED DESCRIPTION

[0027] The present invention will be further specifically described below in conjunction with the embodiments. In the following detailed description, some exemplary embodiments of the present invention are described only by way of illustration. Needless to say, those of ordinary skill in the art will appreciate that the described embodiments may be modified in various ways without departing from the spirit and scope of the present invention. Therefore, the description in the embodiments is illustrative in nature and is not intended to limit the scope of protection of the claims.

[0028] Example 1

[0029] In this embodiment, the production method of chlorinated polyethylene grafted with butyl methacrylate comprises the following steps (the materials of the reaction system are calculated by weight):

[0030] (1) Add 700 parts of 20 (wt)% hydrochloric acid into a reaction kettle, start stirring, add 0.06 parts of propylene oxide and ethylene oxide polymer, 0.04 parts of a composite dispersant (sodium dodecylbenzene sulfonate and sodium p-styrene sulfonate mixed in a mass ratio of 1:1), and add 0.06 parts of hydroxyethyl cellulose as a suspension stabilizer, and mix well;

[0031] (2) Add 100 parts of polyethylene into the reactor and disperse them evenly by stirring. Evacuate the reactor to -0.05 MPa and then seal it and heat it to 50°C. Pass chlorine until the pressure reaches 0.5 MPa. After the temperature reaches 110°C, keep the temperature constant. After the chlorine flow reaches 120 parts, cool it down.

[0032] (3) The reaction material was cooled to 50°C, and the reactor was purged with nitrogen to replace the atmosphere with nitrogen; 5 parts of cuprous chloride and 5 parts of triphenylphosphine powder were added, and after stirring and dispersing evenly, 25 parts of butyl methacrylate and 5 parts of butyl acrylate were added. After the reaction was completed, the material was centrifuged and filtered;

[0033] (4) The centrifuged material is washed with ethanol to remove the grafted monomer, and then washed with ethyl acetate to remove triphenylphosphine. The washed material is dried to obtain the grafted product - chlorinated polyethylene grafted with butyl methacrylate.

[0034] According to the Soxhlet extraction method, the grafting rate of chlorinated polyethylene grafted with butyl methacrylate in this embodiment was measured to be 4.8%.

[0035] Example 2

[0036] In this embodiment, the production method of chlorinated polyethylene grafted with butyl methacrylate comprises the following steps (the materials of the reaction system are calculated by weight):

[0037] (1) Add 550 parts of 20 (wt)% hydrochloric acid into a reaction kettle, start stirring, add 0.06 parts of propylene oxide and ethylene oxide polymer, 0.04 parts of a composite dispersant (sodium dodecylbenzene sulfonate and sodium p-styrene sulfonate mixed in a mass ratio of 1:1), and add 0.06 parts of hydroxyethyl cellulose as a suspension stabilizer, and mix well;

[0038] (2) Add 100 parts of polyethylene into the reactor and disperse them evenly by stirring. Evacuate the reactor to -0.05 MPa and then seal it and heat it to 50°C. Pass chlorine until the pressure reaches 0.5 MPa. After the temperature reaches 110°C, keep the temperature constant. After the chlorine flow reaches 120 parts, cool it down.

[0039] (3) The reaction material was cooled to 50°C, and the reactor was purged with nitrogen to replace the atmosphere with nitrogen; 5 parts of cuprous chloride and 5 parts of triphenylphosphine powder were added, and after stirring and dispersing evenly, 25 parts of butyl methacrylate and 5 parts of butyl acrylate were added. After the reaction was completed, the material was centrifuged and filtered;

[0040] (4) The centrifuged material is washed with ethanol to remove the grafted monomer, and then washed with ethyl acetate to remove triphenylphosphine. The washed material is dried to obtain the grafted product - chlorinated polyethylene grafted with butyl methacrylate.

[0041] According to the Soxhlet extraction method, the grafting rate of chlorinated polyethylene grafted with butyl methacrylate in this embodiment was measured to be 5.3%.

[0042] Example 3

[0043] In this embodiment, the production method of chlorinated polyethylene grafted with butyl methacrylate comprises the following steps (the materials of the reaction system are calculated by weight):

[0044] (1) Add 400 parts of 20 (wt)% hydrochloric acid into a reaction kettle, start stirring, add 0.06 parts of propylene oxide and ethylene oxide polymer, 0.04 parts of a composite dispersant (sodium dodecylbenzene sulfonate and sodium p-styrene sulfonate mixed in a mass ratio of 1:1), and add 0.06 parts of hydroxyethyl cellulose as a suspension stabilizer, and mix well;

[0045] (2) Add 100 parts of polyethylene into the reactor and disperse them evenly by stirring. Evacuate the reactor to -0.05 MPa and then seal it and heat it to 50°C. Pass chlorine until the pressure reaches 0.5 MPa. After the temperature reaches 110°C, keep the temperature constant. After the chlorine flow reaches 120 parts, cool it down.

[0046] (3) The reaction material was cooled to 50°C, and the reactor was purged with nitrogen to replace the atmosphere with nitrogen; 5 parts of cuprous chloride and 5 parts of triphenylphosphine powder were added, and after stirring and dispersing evenly, 25 parts of butyl methacrylate and 5 parts of butyl acrylate were added. After the reaction was completed, the material was centrifuged and filtered;

[0047] (4) The centrifuged material is washed with ethanol to remove the grafted monomer, and then washed with ethyl acetate to remove triphenylphosphine. The washed material is dried to obtain the grafted product - chlorinated polyethylene grafted with butyl methacrylate.

[0048] According to the Soxhlet extraction method, the grafting rate of chlorinated polyethylene grafted with butyl methacrylate in this embodiment was measured to be 6.6%.

[0049] Comparative Example 1

[0050] At room temperature, 700 parts of 20 (wt)% hydrochloric acid are added to a reactor, and 100 parts of polyethylene, 0.06 parts of propylene oxide and ethylene oxide polymer, 0.04 parts of a composite dispersant (sodium dodecylbenzene sulfonate and sodium p-styrene sulfonate are mixed in a mass ratio of 1:1) are added, and 0.06 parts of hydroxyethyl cellulose are added as a suspension stabilizer, and mixed evenly; after stirring evenly, the reactor is sealed and evacuated to -0.05MPa, and after the temperature is raised to 50°C, chlorine is passed; as the amount of chlorine passed increases, the pressure gradually reaches 0.5MPa, and the reaction temperature gradually rises to 110°C and the temperature is kept constant; after the amount of chlorine passed reaches 120 parts, the temperature is lowered to 50°C, and after nitrogen replacement, the material is filtered, neutralized, washed with water, and dried in a drying system to obtain chlorinated polyethylene powder.

[0051] Comparative Example 2

[0052] At room temperature, 550 parts of 20 (wt)% hydrochloric acid are added into a reactor, and 100 parts of polyethylene, 0.06 parts of propylene oxide and ethylene oxide polymer, 0.04 parts of a composite dispersant (sodium dodecylbenzene sulfonate and sodium p-styrene sulfonate are mixed in a mass ratio of 1:1) are added, and 0.06 parts of hydroxyethyl cellulose are added as a suspension stabilizer, and mixed evenly; after stirring evenly, the reactor is sealed and evacuated to -0.05MPa, and after the temperature is raised to 50°C, chlorine is passed; as the amount of chlorine passed increases, the pressure gradually reaches 0.5MPa, and the reaction temperature gradually rises to 110°C and the temperature is kept constant; after the amount of chlorine passed reaches 120 parts, the temperature is lowered to 50°C, and after nitrogen replacement, the material is filtered, neutralized, washed with water, and dried in a drying system to obtain chlorinated polyethylene powder.

[0053] Comparative Example 3

[0054] At room temperature, 400 parts of 20 (wt)% hydrochloric acid are added to a reactor, and 100 parts of polyethylene, 0.06 parts of propylene oxide and ethylene oxide polymer, 0.04 parts of a composite dispersant (sodium dodecylbenzene sulfonate and sodium p-styrene sulfonate are mixed in a mass ratio of 1:1) are added, and 0.06 parts of hydroxyethyl cellulose are added as a suspension stabilizer, and mixed evenly; after stirring evenly, the reactor is sealed and evacuated to -0.05MPa, and after the temperature is raised to 50°C, chlorine is passed; as the amount of chlorine passed increases, the pressure gradually reaches 0.5MPa, and the reaction temperature gradually rises to 110°C and the temperature is kept constant; after the amount of chlorine passed reaches 120 parts, the temperature is lowered to 50°C, and after nitrogen replacement, the material is filtered, neutralized, washed with water, and dried in a drying system to obtain chlorinated polyethylene powder.

[0055] The infrared spectra of the grafted product obtained in Example 1 and the chlorinated polyethylene obtained in Comparative Example 1 are as follows: Figure 1 As shown, from the comparison of the infrared spectrum, it can be seen that the product obtained in Example 1 is chlorinated polyethylene grafted with butyl methacrylate.

[0056] The chlorinated polyethylene grafted with butyl methacrylate samples obtained in Examples 1 to 3 and the chlorinated polyethylene obtained in Comparative Examples 1 to 3 were subjected to rubber refining in an open mill and their properties were tested. The test results are shown in the following table:

[0057]

[0058] It can be seen from Examples 1 to 3 and Comparative Examples 1 to 3 that the chlorinated polyethylene grafted with butyl methacrylate product can be directly prepared by subjecting polyethylene to chlorination reaction and atom transfer radical polymerization reaction. Compared with chlorinated polyethylene, this product has greater breaking strength and breaking elongation, enriching the product application range.

[0059] The present invention adopts suspension polymerization grafting to ensure that the prepared chlorinated polyethylene grafted butyl methacrylate is grafted uniformly, and a chlorinated polyethylene grafted butyl methacrylate product with a grafting rate of 4.8% to 6.6% can be obtained, and the product quality is stable. At the same time, due to the use of atom transfer radical polymerization, the monomer waste caused by monomer polymerization when preparing the grafted compound by in-situ polymerization is avoided, and the disadvantage of poor distribution uniformity of the monomer in the molecular chain during melt grafting is also avoided, thereby greatly improving the quality of the chlorinated polyethylene grafted butyl methacrylate product, so that the chlorinated polyethylene grafted butyl methacrylate can be applied in more fields.

[0060] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for producing chlorinated polyethylene grafted with butyl methacrylate, characterized in that: The steps include: S1. Add polyethylene and various additives into a reactor containing hydrochloric acid and stir evenly; the additives include dispersants and suspension stabilizers; S2. When the temperature rises to 45-55°C, chlorine gas is introduced into the reactor, and the reaction temperature is controlled to be 100-110°C, the pressure is 0.4-0.5Mpa, and the time is 3-5h; S3, after the chlorination reaction is completed, the pressure is released, the reactor is purged with nitrogen, replaced with a nitrogen atmosphere, the temperature is lowered to 40-50°C, a catalyst and a grafting monomer are added, and the temperature of the grafting stage is controlled to be 40-50°C for 6-8h; the catalyst is a cuprous chloride / bipyridine system, a cuprous chloride / o-phenanthroline system, a carboxy cuprous / bipyridine system, a ruthenium chloride / triphenylphosphine system, a ferrous chloride / triphenylphosphine system or a cuprous chloride / triphenylphosphine system; S4, centrifuging the material after the grafting reaction, washing with an organic solvent and then drying to obtain chlorinated polyethylene grafted with butyl methacrylate.

2. The method for producing chlorinated polyethylene grafted with butyl methacrylate according to claim 1, characterized in that: In step S1, the mass percentage concentration of the hydrochloric acid used is 18% to 22%.

3. The method for producing chlorinated polyethylene grafted with butyl methacrylate according to claim 1, characterized in that: The dispersant is one or a combination of any proportion of sodium methacrylate-2-ethanesulfonate, propylene oxide and ethylene oxide polymer, sodium dodecyl sulfate, nonylphenol polyoxyethylene ether, octylphenol polyoxyethylene ether and composite emulsifier.

4. The method for producing chlorinated polyethylene grafted with butyl methacrylate according to claim 1, characterized in that: The suspension stabilizer is one or a combination of any proportion of hydroxyethyl cellulose, polyvinyl alcohol, polyvinyl pyrrolidone and sodium polyacrylate.

5. The method for producing chlorinated polyethylene grafted with butyl methacrylate as claimed in claim 2, characterized in that: In step S1, the mass ratio of polyethylene, dispersant, suspension stabilizer and hydrochloric acid is 100: 0.02-0.8: 0.02-0.8: 400-700.

6. The method for producing chlorinated polyethylene grafted with butyl methacrylate according to claim 1, characterized in that: In step S3, the grafting monomer includes butyl methacrylate and a second monomer, and the mass ratio of the butyl methacrylate to the second monomer is 25-40:5-8.

7. The method for producing chlorinated polyethylene grafted with butyl methacrylate according to claim 6, characterized in that: The second monomer is one or a combination of any proportion of acrylic acid, methyl acrylate, ethyl acrylate, glycidyl acrylate and butyl acrylate.

8. The method for producing chlorinated polyethylene grafted with butyl methacrylate according to any one of claims 1 to 7, characterized in that: In step S4, the organic solvent is one of ethanol, ether, methanol, ethyl acetate and dichloromethane.

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