KR20220037783A - Method for halogenating isobutene-isoprene copolymer - Google Patents

Abstract

The present invention relates to a method for halogenating an isobutene-isoprene copolymer. The method for halogenating an isobutene-isoprene copolymer includes: (S1) a step of preparing a mixed solution containing an isobutene-isoprene copolymer, a hydrocarbon solvent, and an alcohol; and (S2) a step of making the mixed solution react with a halogenating agent to halogenate the isobutene-isoprene copolymer. According to the present invention, the isobutene-isoprene copolymer can be effectively used for crosslinking reaction with other rubber.

Description

Halogenation method of isobutene-isoprene copolymer

The present invention relates to a process for the halogenation of isobutene-isoprene copolymers.

Butyl rubber (isobutene-isoprene rubber, IIR) is an isobutene-isoprene copolymer containing isobutene and about 1 to 6% isoprene, and has chemical resistance, moisture resistance, electrical insulation, etc. Because it is excellent, it is used for applications such as pressure-sensitive adhesive compositions and pressure-sensitive adhesive sheets. Isobutene, the main component of butyl rubber, exhibits excellent gas barrier properties, antioxidant properties, and thermal stability, but has a disadvantage that it cannot participate in the crosslinking reaction because there is no additional functional group in the polymer chain. To compensate for this, butyl rubber has unsaturated functional groups even after polymerization isoprene having a certain amount is included. However, butyl rubber has a disadvantage in that it still lacks crosslinking reactivity because the content of isoprene is small.

To solve this problem, butyl rubber undergoes an additional halogenation reaction on the double bond of isoprene and is converted to halogenated butyl rubber to be crosslinked/compounded with other rubbers. It is widely used as a main material such as

Among these halogenation reactions, for example, in the case of a bromination reaction, all butyl rubber cannot be converted to a bromination functional group having the same structure, and unreacted isoprene (structure I), secondary allyl bromide (structure II, exo-allylic bromide), primary A product including allyl bromide (structure III, endo-allylic bromide) and the like is prepared.

Of these, Structure II is an important structure that directly affects crosslinking performance when undergoing a crosslinking reaction with other rubbers, but HBr, a by-product of the bromination reaction, is rearranged from Structure II to Structure III by ionized bromide ions (Br ^- ) ( rearrangement) may occur.

Structure III produced by the structural rearrangement as described above exhibits undesirable crosslinking performance, so it prevents such rearrangement from proceeding in the halogenation process of butyl rubber, and induces a high content of functional groups of structure II in halogenated butyl rubber. It acts as an important factor in improving the crosslinking properties of the halogenated isobutene-isoprene copolymer.

Korean Patent Publication KR 10-2010-0099125 A

An object of the present invention is to suppress a side reaction in which a secondary allyl halogen functional group is rearranged with a primary allyl halogen functional group in a reaction for halogenating an isobutene-isoprene copolymer, thereby containing a secondary allyl halogen functional group having a terminal double bond in a high content It is to provide a method for producing a halogenated isobutene-isoprene copolymer.

In order to solve the above problems, the present invention comprises the steps of (S1) preparing a mixed solution comprising an isobutene-isoprene copolymer, a hydrocarbon solvent and an alcohol; and (S2) reacting the mixed solution with a halogenating agent to halogenate the isobutene-isoprene copolymer.

When the isobutene-isoprene copolymer is halogenated using the present invention, the content of secondary allyl halogen functional groups in the halogenated isobutene-isoprene copolymer can be increased by preventing rearrangement of secondary allyl halogen functional groups, and thus other rubbers It can be used more effectively for cross-linking reaction with and has the advantage of easy industrial use.

Hereinafter, the present invention will be described in more detail to help the understanding of the present invention.

The terms or words used in the description and claims of the present invention should not be construed as being limited to their ordinary or dictionary meanings, and the inventor appropriately defines the concept of the term in order to best describe his invention. Based on the principle that it can be done, it should be interpreted as meaning and concept consistent with the technical idea of the present invention.

The present invention comprises the steps of (S1) preparing a mixed solution containing an isobutene-isoprene copolymer, a hydrocarbon solvent and an alcohol; and (S2) reacting the mixed solution with a halogenating agent to halogenate the isobutene-isoprene copolymer.

Hydrogen halide (for example, HBr) produced as a by-product in the halogenation reaction of the isobutene-isoprene copolymer further reacts with the halogenated isobutene-isoprene copolymer, and secondary allyl bromide ( Structure II, exo-allylic bromide) to primary allyl bromide (Structure III, endo-allylic bromide) to the primary allyl bromide (Structure III, endo-allylic bromide) occurs as a side reaction occurs, so in order to keep the crosslinking performance of the halogenated isobutene-isoprene copolymer constant, this structure It is important to avoid rearrangement.

Conventionally, in order to prevent the rearrangement of structure II into structure III as described above, water is added to the halogenation reaction to dissolve the hydrogen halide in the aqueous layer, and the halogenated isobutene-isoprene copolymer is separated from the organic layer in which it is present. A method of physically preventing the copolymer from contacting has been used. In this case, since the hydrogen halide and the copolymer are in separate layers, rearrangement can be suppressed by lowering the possibility of contact. Even in this case, there was still a limit in that the ratio of structure II could not be implemented above a certain level even in this case, since the possibility of a realignment reaction immediately increases when even a ray is in contact.

Therefore, it is important to separate the hydrogen halide from the organic layer and at the same time reduce the tendency to be ionized into halide ions to prevent the structure II rearrangement reaction from proceeding as much as possible.

Accordingly, in the present invention, alcohol was used as an additive in the mixed solution for the halogenation reaction. Alcohol has a high affinity for hydrogen halide, so it can be efficiently dissolved and separated from the organic layer. However, the intrinsic pKa of oxonium ions is small, so the tendency of hydrogen halide to be ionized into halide ions is low, and as a result, the number of halide ions is reduced. By reducing it, it is possible to effectively suppress structural rearrangement.

In addition, in the present invention, since structural rearrangement can be effectively prevented by using alcohol as described above, unlike the conventional method in which hydrogen halide is oxidized with an oxidizing agent and reused as a halogenating agent, structure II can be achieved at an equivalent or higher level without using an oxidizing agent. can be implemented with a high content of The oxidizing agent may have a side reaction with the non-halogenated isobutene-isoprene copolymer in the reaction system, and in this case, there may be a problem of changing the physical properties of the isobutene-isoprene copolymer in an unexpected direction. In the present invention, side effects due to the use of the oxidizing agent were also prevented by making the ratio of structure II appear high without using the oxidizing agent.

Step (S1)

Step (S1) is a step of preparing a mixed solution including an isobutene-isoprene copolymer, a hydrocarbon solvent and an alcohol, and preparing a reactant for halogenating the isobutene-isoprene copolymer.

In the present invention, the prevention of structural rearrangement of the halogenated isobutene-isoprene copolymer is a principle of preventing contact with the halogenated isobutene-isoprene copolymer by separating the hydrogen halide generated after halogenation into an aqueous layer. Therefore, it is important to quickly separate the hydrogen halide into a separate aqueous layer after halogenation of the isobutene-isoprene copolymer before further reaction with the hydrogen halide occurs. Therefore, it is preferable not to separately add water during the halogenation reaction, but to add alcohol into the reaction system before the halogenation starts as in step (S1).

In the present invention, the alcohol may be 0.1 to 20% by weight based on the hydrocarbon solvent, specifically, 0.1% by weight or more, 0.5% by weight or more, 10% by weight or more, 20% by weight or less, 15% by weight or less.

If the alcohol is less than 0.1% by weight based on the hydrocarbon solvent, the effect of suppressing by-products cannot be sufficiently realized and the rearrangement of the isobutene-isoprene copolymer cannot be prevented, so that deterioration of physical properties may appear. Alcohol may not only reduce economic efficiency, but also consume a lot of energy in the drying process after halogenation is completed.

In the present invention, the type of the alcohol is not particularly limited, but in consideration of the ease of drying after the completion of the halogenation reaction of the isobutene-isoprene copolymer, it may be an alcohol having 1 to 4 carbon atoms, for example, methanol, ethanol, propanol, Isopropyl alcohol, 1-butanol, 2-butanol, tert-butanol, or mixtures thereof may be used.

In the present invention, the isobutene-isoprene copolymer may be 1 to 10 mol% based on the isobutene-isoprene copolymer, or 1 to 8 mol%, or 1 to 5 mol% of isoprene may be used. The present invention is not limited thereto, and may be applied to the present invention by selecting a copolymer having an appropriate composition and molecular weight according to the purpose or use.

The isobutene-isoprene copolymer can be obtained by purchasing a commercially available one or preparing by copolymerizing isobutene and isoprene. When applying to the present invention after preparing a copolymer by copolymerizing isobutene and isoprene, if alcohol is used as a polymerization terminator in the copolymerization reaction, the halogenation reaction can be performed without separately removing the residual polymerization terminator prior to the halogenation reaction. It can be carried out quickly, which has the effect of shortening the process and increasing efficiency.

In the present invention, the isobutene-isoprene copolymer may be 5 to 25 wt% based on a mixed solution containing the isobutene-isoprene copolymer, a hydrocarbon solvent and an alcohol, specifically, 5 wt% or more, 10 wt% or more, 15 wt% or more, 25 wt% or less, 20 wt% or less, or 15 wt%.

When the amount of the isobutene-isoprene copolymer is less than 5% by weight based on the mixed solution, productivity may decrease, and when it is more than 25% by weight based on the mixed solution, solubility in the mixed solution may decrease and the halogenation reaction may not proceed sufficiently.

In the present invention, the hydrocarbon solvent may be an aliphatic hydrocarbon solvent or an aromatic hydrocarbon solvent. For example, the aliphatic hydrocarbon solvent may be at least one selected from the group consisting of butane, pentane, neo pentane, hexane, cyclohexane, methylcyclohexane, heptane and octane, and the aromatic hydrocarbon solvent is benzene, toluene, and xylene. And it may be at least one selected from the group consisting of ethylbenzene, but is not limited thereto.

Step (S2)

The step (S2) is a step of halogenating the isobutene-isoprene copolymer by reacting the solution prepared in step (S1) with a halogenating agent. At this time, as the halogen atom is positioned at the hydrogen position of the isobutene-isoprene copolymer, hydrogen halide is generated as a by-product.

In the present invention, the halogenating agent may be a bromine molecule (Br ₂ ) or a chlorine molecule (Cl ₂ ), specifically, a bromine molecule (Br ₂ ).

In the present invention, the halogenating agent may be 0.6 to 1.2 equivalents based on 1 equivalent of the double bond contained in the isobutene-isoprene copolymer, and specifically 0.6 equivalent or more, 0.8 equivalent or more, 1.2 equivalent or less, 1.0 equivalent or less.

If the amount of the halogenating agent is less than 0.6 equivalents based on 1 equivalent of the double bond contained in the isobutene-isoprene copolymer, the halogenation reaction may not proceed sufficiently, and the crosslinking property of the isobutene-isoprene copolymer may not be sufficiently improved, and the isobutene-isoprene copolymer If the amount exceeds 1.2 equivalents based on 1 equivalent of the double bond contained in the coalescence, there is a fear that an overreaction may proceed due to an excess of the halogenating agent, resulting in a decrease in the structure I content.

In the present invention, the halogenating agent may be dissolved in a hydrocarbon solvent and used in the form of a composition, and the hydrocarbon solvent may be an aliphatic hydrocarbon solvent or an aromatic hydrocarbon solvent. For example, the aliphatic hydrocarbon solvent may be at least one selected from the group consisting of butane, pentane, neo pentane, hexane, cyclohexane, methylcyclohexane, heptane and octane, and the aromatic hydrocarbon solvent is benzene, toluene, and xylene. And it may be at least one selected from the group consisting of ethylbenzene, but is not limited thereto.

Based on the solution in which the halogenating agent is dissolved in the hydrocarbon solvent, 10 wt% or more, 15 wt% or more, 50 wt% or less, 30 wt% or less, for example, 20 wt% or less, may be dissolved to be used, but is not limited thereto.

In the present invention, the halogenation of step (S2) may be carried out at 10 to 80 °C, specifically, at 10 °C or higher, 30 °C or higher, 40 °C or higher, 80 °C or lower, 60 °C or lower.

When the halogenation temperature is less than 10 °C, the reaction rate is excessively fast, so it may be difficult to control the reaction.

In the present invention, the halogenation of step (S2) may be performed for 10 seconds to 60 minutes, and specifically, it may be performed for 10 seconds or more, 30 seconds or more, 1 minute or more, 60 minutes or less, and 30 minutes or less. .

If the halogenation time is less than 10 seconds, the halogenation of the isobutene-isoprene copolymer may not proceed sufficiently due to insufficient reaction time, and if it exceeds 60 minutes, the possibility of additional side reactions after halogenation is increased.

According to the halogenation method of the present invention, a part of the repeating unit represented by the following structure I (isoprene-derived repeating unit) is converted into a repeating unit represented by the following structure II or a repeating unit represented by the structure III, in particular the present invention Since the rearrangement of Structure II into Structure III was prevented in , a halogenated isobutene-isoprene copolymer including a high content of the repeating unit represented by Structure II can be prepared by using the halogenation method of the present invention.

[Structure I]

[Structure II]

[Structure III]

In structure II and structure III above,

X is a halogen group.

Specifically, the halogenated isobutene-isoprene copolymer prepared by the halogenation method of the present invention may contain 0.90 mol% or more, 0.91 mol% or more, 0.92 mol% or more, of the repeating unit represented by the following structure II. .

Further, the percentage of moles of the repeating unit represented by Structure II, that is, the ratio (%) of Structure II, to the total number of moles of the repeating unit represented by Structure II and the repeating unit represented by Structure III may be greater than 91%.

Structure II ratio (%) = [(moles of structure II)/(number of moles of structure II + moles of structure III)] × 100

Specifically, the structure II ratio (%) may be 92% or more, 93% or more, 94% or more, 95% or more, 97% or more. The structure II ratio (%) represents the ratio of structure II to halogenated repeating units (structure II and structure III), and the value increases as the structural rearrangement from structure II to structure III is suppressed.

That is, as described above, in step (S2), the isoprene-derived repeating unit is converted into a repeating unit represented by Structure II or Structure III by halogenation. A halogenated isobutene-isoprene copolymer is prepared.

The halogenation method of the isobutene-isoprene copolymer of the present invention may further include (S3) reacting with a basic material to neutralize the hydrogen halide generated in step (S2).

As described above, in step (S2), after the isobutene-isoprene copolymer is halogenated, hydrogen halide is generated as a by-product and dissolved in the aqueous layer. Also, even a trace amount of hydrogen halide is ionized and is present in the aqueous layer as halide ions. In step (S3), hydrogen halide and halide ions may be removed by contacting with a basic material to cause an acid-base reaction.

In addition, since the basic substance also reacts with a halogenating agent, such as a bromine molecule, it is possible to inhibit the further reaction of the halogenated isobutene-isoprene copolymer, and consequently, there is an effect of inhibiting structural rearrangement along with neutralization of the acidic substance. .

The basic material is not particularly limited, but a basic material having a pH of 10 to 14 may be used as a material suitable for realizing the above purpose, and alkali metal hydroxide, alkaline earth metal hydroxide, alkali metal carbonate, alkaline earth metal carbonate, etc. may be used. there is. For example, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, combinations thereof, and the like, but are not limited thereto.

The basic material may be used in the amount of 2 to 5 equivalents based on the halogenating agent used in step (S2), and when the basic material is less than 2 equivalents based on the halogenating agent, sufficient quenching may not be achieved, and more than 5 equivalents based on the halogenating agent In this case, since more basic material than necessary is added, the economic feasibility and efficiency of the reaction process may be reduced.

In the present invention, the neutralization of step (S3) may be carried out at 10 to 40 °C, specifically, at 10 °C or higher, 15 °C or higher, 20 °C or higher, 40 °C or lower, 30 °C or lower.

In addition, the neutralization of step (S3) may be performed for 3 to 15 minutes, specifically, may be performed for 3 minutes or more, 5 minutes or more, 15 minutes or less, and 10 minutes or less. If the execution time of the step (S3) is less than 3 minutes, quenching may not be sufficiently performed, and an unreacted halogenating agent, which is a toxic substance, may remain.

Example

Hereinafter, the present invention will be described in more detail by way of Examples. However, the following examples are provided to illustrate the present invention, and the scope of the present invention is not limited thereto.

Example 1

To prepare the butyl rubber solution, 0.5 g of butyl rubber (isoprene content = 1.8 mol%), 2.8 g of n-Hexane, and 0.28 g of methanol (10% by weight based on hexane) as an additive are put into a shaker and dissolved for more than 12 hours made it Afterwards, the mixed solution was stirred for 30 minutes in a heating mantle set to a reaction temperature of 40 °C. Thereafter, 0.17 mL of a previously prepared bromine solution (20 wt% solution in hexane) was added to carry out the bromination reaction for 60 seconds.

Then, 0.32 mL of NaOH aqueous solution (1M) was added, neutralized at room temperature for 10 minutes, and dried through a vacuum oven to prepare a brominated isobutene-isoprene copolymer.

Example 2

A brominated isobutene-isoprene copolymer was prepared in the same manner as in Example 1, except that 0.28 g of ethanol (10% by weight based on hexane) was used as an additive instead of 0.28g of methanol (10% by weight based on hexane).

Example 3

A brominated isobutene-isoprene copolymer was prepared in the same manner as in Example 1, except that 0.28 g of isopropyl alcohol (10 wt% based on hexane) was used as an additive instead of 0.28 g of methanol (10 wt% based on hexane).

Example 4

A brominated isobutene-isoprene copolymer was prepared in the same manner as in Example 1, except that 0.14 g (5 wt% based on hexane) of methanol was used as an additive.

Comparative Example 1

A brominated isobutene-isoprene copolymer was prepared in the same manner as in Example 1, except that no additives were used.

Comparative Example 2

A brominated isobutene-isoprene copolymer was prepared in the same manner as in Example 1, except that 0.28 g of water (10% by weight based on hexane) was used as an additive instead of 0.28 g of methanol (10% by weight based on hexane).

Comparative Example 3

As an additive, 0.28 g of water (10% by weight based on hexane) was used instead of 0.28g of methanol (10% by weight based on hexane), and 0.28g (10% by weight based on hexane) of methanol was mixed in NaOH aqueous solution. A brominated isobutene-isoprene copolymer was prepared in the same manner as in Example 1.

Comparative Example 4

A mixed solution was prepared using water instead of methanol as an additive. Then, NaOCl was added as an oxidizing agent (1 equivalent based on a halogenating agent) and pre-mixed for 1 minute, then 0.08 mL of a bromine solution (20 wt% solution in hexane) was added to carry out the bromination reaction for 5 minutes.

Then, 0.32 mL of NaOH aqueous solution (1M) was added, neutralized at room temperature for 10 minutes, and dried through a vacuum oven to prepare a brominated isobutene-isoprene copolymer.

Experimental Example 1

The ratio of the internal structure was calculated through ¹ H NMR (CDCl ₃ ) analysis of the brominated isobutene-isoprene copolymer of the Examples and Comparative Examples.

(1) Structure I (isoprene repeat unit) content (mol%)

- Structure I content (mol%) = [(moles of structure I)/( moles of structure A + moles of structure I + moles of structure II + moles of structure III)] × 100

(2) Structure II content (mol%)

- Structure II content (mol%) = [(moles of structure II)/(moles of structure A + moles of structure I + moles of structure II + moles of structure III)] × 100

(3) Structure III content (mol%)

- Structure III content (mol%) = [(moles of structure III)/(moles of structure A + moles of structure I + moles of structure II + moles of structure III)] × 100

(4) Structure II ratio (%)

- Ratio of structure II (%) = [(moles of structure II)/(number of moles of structure II + moles of structure III)] × 100

Structure I (mol%) Structure II (mol%) Structure III (mol%) Structure II percentage (%) Example 1 0.55 0.95 0.02 98 Example 2 0.53 0.93 0.03 97 Example 3 0.57 0.92 0.02 98 Example 4 0.58 0.92 0.02 98 Comparative Example 1 0.47 0.52 0.42 55 Comparative Example 2 0.52 0.88 0.09 91 Comparative Example 3 0.49 0.89 0.09 91 Comparative Example 4 1.04 0.52 0.06 90

As can be seen from the above results, in the examples in which the isobutene-isoprene copolymer was brominated according to the preparation method of the present invention, a brominated isobutene-isoprene copolymer having a higher ratio of structure II was prepared, and thus excellent crosslinking Specifically, in Comparative Examples 1 to 3, the bromination reaction itself proceeded at a level similar to that of Example, but in Comparative Example 1 without alcohol, structural rearrangement occurred and the structure II content was lowered. It was very low, and in Comparative Examples 2 and 3, since water was used instead of alcohol, a lot of bromide ions were generated, and structural rearrangement occurred more than in Examples, confirming that the content of structure II was low. In particular, in Comparative Example 3, methanol was added in the neutralization step after bromination, but in this case, it was found that methanol did not prevent structural rearrangement.

In Comparative Example 4, an oxidizing agent was added for reuse of HBr while using water as an additive, but a brominated isobutene-isoprene copolymer having a lower structure II ratio than that of Example was nevertheless prepared.

As described above, by carrying out the halogenation reaction of the isobutene-isoprene copolymer in the presence of alcohol, a halogenated isobutene-isoprene copolymer containing a high proportion of functional groups of Structure II can be prepared without using an oxidizing agent.

Claims (12)

(S1) preparing a mixed solution containing an isobutene-isoprene copolymer, a hydrocarbon solvent, and an alcohol; and
(S2) halogenating the isobutene-isoprene copolymer by reacting the mixed solution with a halogenating agent;
The method according to claim 1,
(S3) reacting with a basic material to neutralize the hydrogen halide generated in step (S2); isobutene-isoprene copolymer halogenation method further comprising a.
3. The method according to claim 2,
The basic material is at least one selected from the group consisting of sodium hydroxide, potassium hydroxide, sodium carbonate and potassium carbonate.
The method according to claim 1,
The alcohol is at least one selected from the group consisting of methanol, ethanol, propanol, isopropyl alcohol, 1-butanol, 2-butanol and tert-butanol.
The method according to claim 1,
The halogenation method of the isobutene-isoprene copolymer is 5 to 25% by weight based on the mixed solution of the isobutene-isoprene copolymer.
The method according to claim 1,
The alcohol is 0.1 to 20% by weight based on a hydrocarbon solvent. Halogenation method of the isobutene-isoprene copolymer.
The method according to claim 1,
The halogenation method of the isobutene-isoprene copolymer, wherein the halogenating agent is 0.6 to 1.2 equivalents based on 1 equivalent of the double bond contained in the isobutene-isoprene copolymer.
The method according to claim 1,
The halogenation method of the isobutene-isoprene copolymer, wherein the halogenating agent is a bromine molecule (Br ₂ ) or a chlorine molecule (Cl ₂ ).
The method according to claim 1,
The halogenation is a halogenation method of isobutene-isoprene copolymer is carried out at 10 to 80 ℃.
The method according to claim 1,
The halogenation method is isobutene-isoprene copolymer is carried out for 10 seconds to 60 minutes.
The method according to claim 1,
Halogenation method of an isobutene-isoprene copolymer prepared by the halogenation method, wherein the halogenated isobutene-isoprene copolymer contains 0.90 mol% or more of a repeating unit represented by the following structure II:
[Structure II]

In structure II,
X is a halogen group.
The method according to claim 1,
In the halogenated isobutene-isoprene copolymer prepared by the above halogenation method, the percentage of the number of moles of the repeating unit represented by Structure II to the total number of moles of the repeating unit represented by Structure II and Structure III is 92% or more of isopartic acid. Halogenation method of ten-isoprene copolymer:
[Structure II]

[Structure III]

In structure II and structure III above,
X is a halogen group.