JPH0790016A - Polyethylene modified with fluorinated alkyl and its production - Google Patents

Abstract

PURPOSE:To obtain a new polyethylene modified with fluorinated alkyl and having excellent oil and water repellecies in high yield and purity by producing a living polyethylene using an alkyllithium/t-diamine initiator and successively reacting the product with two specific kinds of compounds. CONSTITUTION:Ethylene is subjected to living polymerization in the presence of an initiator consisting of a 1-6C straight or a branched alkyllithium (e.g. methyllithium) and a t-diamine (preferably tetramethylethylenediamine, etc.). The polymerization product is reacted with a formic acid ester preferably by slowly adding the ester little by little to the system and then with a fluorinated alkylcarboxylic acid halide of a formula I (Rf is a 2-17C perfluoroalkyl or a perfluoropropylene oxide oligomer having a polymerization degree of 2-5) (e.g. perfluorooctanoic acid fluoride) to obtain the objective polyethylene of formula II (R1 is a 1-6C straight or branched saturated hydrocarbon chain; (m) and (n) are 10-1,000).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluoroalkyl-modified polyethylene having excellent surface water repellency and oil repellency and a method for producing the same.

[0002]

2. Description of the Related Art Polyethylene has excellent properties in terms of cost and mechanical properties and is widely used. However, since it has no reactive group in its molecular structure, it is chemically modified to have desired properties. Was hard to get. Therefore, in order to make up for such drawbacks, it has been conventionally attempted to introduce a reactive group into polyethylene. For example, the method of copolymerizing with polar monomers such as vinyl acetate and methacrylic acid ester by the high pressure method, or for existing polyethylene,
A method of graft-polymerizing a polar monomer such as maleic anhydride in the presence of a peroxide is known. However, only high-density polyethylene modified products can be obtained by the high-pressure copolymerization method, and homopolymers are by-produced by the graft polymerization method and it is difficult to control the modification amount. It was generally difficult to obtain.

In this regard, it is well known that anionic living polymerization of ethylene is possible with a butyllithium / tertiary diamine type initiator, but the living terminal of ethylene obtained by the anionic living polymerization method has various functional groups. It can be converted into a group. For example, Bergbreiter et al. (J. Polym. Sci., Polym. Chem. 27: 4205-4226 (198
9)) reported that a functional group was introduced at the terminal by reacting a living polyethylene terminal with an electrophile such as carbon dioxide, ethylene oxide, or an alkyl halide, and then these were converted into other functional groups. ing. However, in the case of the reaction between the anionic living terminal and these electrophiles, there were problems such as a low modification rate due to functional groups,
The present inventors have already succeeded in obtaining novel hydroxyl group-modified polyethylene by reacting the anionic living polymerization terminal of ethylene with a specific carbonyl compound, oxygen, formic acid ester and the like.

[0004]

Although polyethylene is originally a material having excellent water repellency, it is expected that further water repellency and oil repellency will be imparted by adding an alkyl fluoride modification to polyethylene. Particularly in the wax region, which is an oligomer of polyethylene, water / oil repellency is often required, and it is considered to be very useful if fluorinated alkyl modification is obtained.

However, conventionally, various types of polar functional groups have been introduced into polyethylene as described above, and the application thereof to a phase transfer catalyst, a fluorescent dye or the like has been studied, but synthesis of fluoroalkyl-modified polyethylene has been conducted. No examples have been reported yet. Therefore, an object of the present invention is to provide a novel polyethylene which is imparted with water / oil repellency by adding alkyl fluoride modification, and a method for producing the same.

[0006]

Under the circumstances, the present inventors have made earnest studies to develop water-repellent / oil-repellent polyethylene, in particular, polyethylene wax, and as a result, bond a fluorinated alkyl group to polyethylene through an ester bond. The novel fluorinated alkyl-modified polyethylene exhibits high water / oil repellency, and the fluorinated alkyl-modified polyethylene reacts with the corresponding hydroxyl halide of the living polymerized polyethylene in a one-pot reaction. The inventors have found that they can be obtained and have completed the present invention.

That is, the present invention provides the following fluoroalkyl-modified polyethylene and a method for producing the same. 1. A fluorinated alkyl-modified polyethylene represented by the following formula (1).

[0008]

[Chemical 3]

(In the formula, R ₁ is a linear or branched saturated hydrocarbon chain having 1 to 6 carbon atoms, m and n are independently integers of 10 to 1000, and Rf is 2 to 17 carbon atoms. It is a perfluoroalkyl group or a perfluoropropylene oxide oligomer having a degree of polymerization of 2 to 5.) 1. A method for producing a fluorinated alkyl-modified polyethylene, which comprises the following steps. 1) Living polymerization of ethylene using a linear or branched alkyllithium / tertiary diamine-based initiator having 1 to 6 carbon atoms; 2) reacting with formic acid ester; and 3) the following formula (2) A step of reacting a fluoroalkylcarboxylic acid halide represented by

[0010]

[Chemical 4]

(In the formula, Rf represents the same as the formula (1) and X represents halogen.) The present invention will be described in more detail below. The fluoroalkyl-modified polyethylene of the present invention has a fluoroalkyl group introduced near the center of a polyethylene chain through an ester bond. The terminal of the molecule is a linear or branched saturated hydrocarbon group having 1 to 6 carbon atoms. That is, it is a methyl group, an ethyl group, an n-butyl group, and the like, and specific examples of the short-chain branch include a 2-methyl group, a 3-methyl group, a 2,2-dimethyl group, and the like. The branched chains at these terminals cause changes in the physical properties of the produced polyethylene such as lowering the melting point when the degree of polymerization is low, but have no effect when the degree of polymerization is high.

The fluorinated alkyl-modified polyethylene of the present invention has two polyethylene chains having a degree of polymerization in the range of 10 to 1000 as an ethylene repeating unit. The degree of polymerization distribution is not particularly limited, but is usually about 1.05 to 5. When the degree of polymerization is about 300 or less, the produced polyethylene shows a wax-like appearance, and when the degree of polymerization is more than 300, it shows a plastics-like appearance and physical properties.

The fluoroalkyl-modified polyethylene of the present invention has a perfluoroalkyl group having 2 to 17 carbon atoms as the fluoroalkyl group (total carbon number is 3 to 18).
A carboxylic acid or a perfluoropropylene oxide oligomer having a degree of polymerization of 2 to 5 is bonded to polyethylene through an ester bond. The perfluoroalkyl group also includes those in which the ω-terminal is substituted with hydrogen or chlorine. The following are mentioned as a specific example of such a perfluoroalkyl group.

[0014]

[Chemical 5]

The following are mentioned as perfluoroalkyl propylene oxide oligomers.

[0016]

[Chemical 6]

It should be noted that a mixture of these in an appropriate ratio is also within the scope of the present invention. In the fluoroalkyl-modified polyethylene of the present invention, the introduction position of the fluoroalkyl group is at the center of the molecular chain on average, but individual molecules may be offset from the center. That is, the fluoroalkyl-modified polyethylene of the present invention is a mixture of polyethylene having fluoroalkyl groups at various positions in the molecular chain. The distribution of the introduction position of this fluorinated alkyl group varies depending on the production conditions, but it exists at a distance of 10 or more as an ethylene repeating unit from one end. The fluorinated alkyl-modified polyethylene of the present invention is obtained by dimerizing the ends of living polymerized polyethylene with a formate ester as described later. In theory,
In living polymerization of a rapid initiation slow growth system, the molecular weight distribution of the polymer produced is a Poisson distribution. As the degree of polymerization increases, the molecular weight approaches monodispersion, so the introduction position of the fluorinated alkyl group is also at the center of the molecular chain. However, in actual polymerization, the molecular weight distribution often expands due to a subtle difference in environment, and in that case, the distribution of the introduction position also expands. Although it is difficult to completely identify the introduction position,
Since the melting point is observed to be lower than that of polyethylene of the same molecular weight having a fluorinated alkyl group near one end, its structure can be estimated.

Next, a method for producing the fluorinated alkyl-modified polyethylene of the present invention will be described. First, as the first step, living polymerization of ethylene with a linear or branched alkyl lithium / tertiary diamine having 1 to 6 carbon atoms is performed.

In living polymerization of polyethylene,
A non-polar aliphatic hydrocarbon solvent is used. Specific examples of such a solvent include pentane, hexane, heptane, octane, cyclohexane and cyclopentane. Preferred is cyclohexane.

Examples of the linear or branched alkyllithium compound having 1 to 6 carbon atoms include methyllithium, ethyllithium, n-butyllithium, s-butyllithium and t.
-Butyl lithium or the like is used. The organic group of the lithium compound used here is introduced into the terminal of the polyethylene produced.

As the tertiary diamine, those having 2 to 3 atoms between two nitrogen atoms are preferably used. Specific examples of such a diamine include tetramethylethylenediamine, dipiperidinoethane, dipyrrolidinoethane, sparteine and the like.

These tertiary diamines are usually used in an amount of 0.1 to 10 equivalents with respect to the alkyl lithium. When the amount of the tertiary diamine used is less than 0.1 equivalent, the polymerization is slow, and the yield of the reaction for introducing an organic group is low, and when it is more than 10 equivalents, many living terminals are deactivated.

Living polymerization of ethylene proceeds by introducing ethylene into the hydrocarbon solution containing the alkyllithium compound and the tertiary diamine. The introduction pressure of ethylene is not particularly limited, but 1 kg / cm ^{2 to} 100 kg / cm ²
Is appropriate. If it is lower than 1 kg / cm ² , the polymerization reaction is too slow, which is not economical. On the other hand, at a high pressure exceeding 100 kg / cm ² , the polymerization is too fast and the reaction becomes difficult to control.

The polymerization is suitably carried out at 0 ° C to 100 ° C.
It is preferably 20 ° C to 80 ° C. If the reaction temperature is lower than 0 ° C., the polymerization reaction will be too slow, and the produced polyethylene will tend to precipitate, which is not preferable. On the other hand, if the reaction temperature exceeds 100 ° C., the living terminal tends to be deactivated, which is not preferable.

The polymerization time varies depending on the polymerization temperature, the concentration of tertiary diamine, the ethylene introduction pressure, etc., but is generally 0.
It takes about 1 to 24 hours. By changing the polymerization time, the molecular weight of the produced polyethylene can be controlled. From the viewpoint of preventing the deactivation of the living terminal, the polymerization time is preferably as short as possible so long as the heat of polymerization can be removed.

In the second step, the living polyethylene produced by the above method is reacted with a formate ester. The alcohol component constituting the formate ester is not particularly limited, but a low molecular weight monohydric alcohol is usually used. Specific examples of such formate ester include methyl formate and ethyl formate. When other carboxylic acid ester is used instead of formic acid ester, polyethylene having a tertiary hydroxyl group can be obtained to some extent.
There are many side reactions such as proton abstraction reaction, and it is not possible to obtain a high introduction rate of fluorinated alkyl groups. This reaction is 2
Since the living end of the molecule is completed by addition to one molecule of formate ester, the addition amount of the formate ester needs to be 1/2 equivalent to the amount of growing living end. In addition, in order to prevent side reactions and reliably obtain the desired product, it is necessary to slowly add the formate ester in small amounts.

The reaction temperature is not particularly limited, but is usually -7.
It is carried out at 8 ° C to 100 ° C, preferably -20 ° C to 70 ° C. The reaction between formic acid ester and living polyethylene is
In a homogeneous system, it will be completed within about 1 minute even at room temperature. However, when the molecular weight of polyethylene is high and a precipitate is formed, the reaction for several minutes to several hours is required.

The polyethylene produced up to the second stage is
Although it has a lithium alkoxide near the center of the molecular chain, as a third step, an acid halide is reacted with this lithium alkoxide terminal. As the acid halide, one having a structure represented by the following formula (2) is preferably used as described above.

[0029]

[Chemical 7]

(In the formula, Rf is a perfluoroalkyl group having 2 to 17 carbon atoms, or a perfluoropropylene oxide oligomer having a polymerization degree of 2 to 5, and X is halogen.) Specific examples of the acid halide are as follows. The following are listed.

[0031]

[Chemical 8]

As described above, these may be mixed in an appropriate ratio and used.

The amount of acid halide used is not particularly limited as long as it is an equimolar amount or more with respect to the living terminal. The reaction temperature is not particularly limited, but is usually -78 ° C to 100 ° C.
It is preferably -30 ° C to 70 ° C. The reaction time is not particularly limited and is usually in the range of 0.1 hour to 24 hours. In a homogeneous system at a relatively high temperature, the reaction proceeds in a short time with a yield of almost 100%.

[0034]

According to the present invention, a novel fluorinated alkyl-modified polyethylene excellent in water / oil repellency can be obtained in high yield and high purity. In particular, the modified polyethylene obtained in the present invention has a high degree of water / oil repellency because it has one fluorinated alkyl group near the center of almost all molecular chains. Further, the molecular weight of the produced polymer is 500 to 20.
A highly water-repellent wax can be obtained by controlling it to about 00.
It can be suitably used as a cosmetic raw material or a high performance lubricant.

[0035]

EXAMPLES The present invention will be described in more detail with reference to the following examples. Example 1 400 ml of dry cyclohexane, 3 ml of tetramethylethylenediamine, n-butyllithium (1.6 mol / liter) were placed in a 1 liter autoclave purged with nitrogen.
5 ml was charged, and ethylene gas was introduced at a pressure of ² kg / cm ² at 50 ° C. After polymerizing for 30 minutes, ethylene gas was removed, and 0.8 ml of ethyl formate was added dropwise thereto. 10
After reacting for a minute, 2.7 ml of perfluorooctanoic acid fluoride was added. After reacting for 15 minutes, the reaction solution was poured into 2 liters of methanol. The solid collected by vacuum filtration was dissolved in boiling toluene, the insoluble matter was removed by filtration under heating, and the filtrate was put into 2 liters of methanol. The solid formed was collected and dried in a 50 ° C. oven under vacuum for 24 hours. Product yield 13.1 g,
As a result of GPC analysis (ortho-dichlorobenzene, 135 ° C., calibrated with polyethylene standard sample) using an apparatus manufactured by Waters, the number average molecular weight of the product was 1690.

¹ H-NMR analysis (Bruker, 200M
Hz, tetrachloroethylene, 80 ° C. DMSO-d ₆ was used as a lock solvent in a double tube, and TM was used as an external standard.
S was used. As a result, the starting terminal methyl group was observed at 0.8 ppm (triplet), the methylene group of the main chain was found at around 1.2 ppm, and the α-methine signal of the ester oxygen at 4.8 ppm (double triplet) was observed. From the integral ratio of each signal, it was found that the number average molecular weight was 1730 and the fluorinated alkyl group introduction rate was 90%.

Example 2 In place of the perfluorooctanoic acid fluoride of Example 1, 3.3 ml of perfluorinated propylene oxide trimer acid fluoride was used for the same synthesis, and 14.0 g of a white waxy solid was obtained. It was The number average molecular weight of the product by GPC was 1780. In addition, ¹ H-NMR analysis showed that the number average molecular weight was 1780 and the fluorinated alkyl group introduction rate was 88%.

Water repellency test The fluoroalkyl-modified polyethylene obtained in Examples 1 and 2 was melt cast on a glass plate, and the contact angle with water and liquid paraffin was measured. As a control, an unmodified polyethylene (Polywax 1000 manufactured by Petrolite) was used as a comparative example. The results are shown in Table 1.

[0039]

[Table 1]

It can be seen that the fluoroalkyl-modified polyethylene of the present invention is excellent in water and oil repellency.

Claims (2)

[Claims] 1. A fluorinated alkyl-modified polyethylene represented by the following formula (1). [Chemical 1] (In the formula, R ₁ is a linear or branched saturated hydrocarbon chain having 1 to 6 carbon atoms, m and n are each independently an integer of 10 to 1000, and Rf is a perfluoroalkyl group having 2 to 17 carbon atoms. Group or a perfluoropropylene oxide oligomer having a polymerization degree of 2 to 5.) 2. A living polymerization of ethylene using a linear or branched alkyllithium / tertiary diamine initiator having 1 to 6 carbon atoms, 2) a step of reacting a formic acid ester, and 3). A step of reacting a fluoroalkylcarboxylic acid halide represented by the following formula (2): (In the formula, Rf represents the same as in the formula (1), and X is halogen.).