JP2001354731A - Dimethacrylate, crosslinking agent, crosslinked resin, and decrosslinking method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dimethacrylate which has the different ester bonds obtained from a secondary hydroxy group and a tertiary hydroxy group, respectively in the molecule, a crosslinking agent containing the same as an effective component, a method for producing the crosslinked resin with the agent, and a method for decrosslinking the crosslinked resin. SOLUTION: The novel dimethacrylate is 2-methyl-2,4-pentane diol dimethacrylate. The crosslinking agent contains the novel dimethacrylate as an effective component. The crosslinked resin is obtained by the radical polymerization of a vinyl monomer with 2-methyl-2,4-pentane diol dimethacrylate. The decrosslinking method is characterized by heating the crosslinked resin at 180-300 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a dimethacrylate having a specific structure, a crosslinking agent containing the same as an active ingredient, a crosslinked resin obtained by using the same, and a method for decrosslinking the crosslinked resin.

[0002]

2. Description of the Related Art Dimethacrylates represented by diethylene glycol dimethacrylate and 1,6-hexanediol dimethacrylate are useful as a crosslinking agent because they have two radically polymerizable vinyl groups in one molecule. For example, Polymer Chemistry (Vol. 27, No. 297, p. 65, 1
970) discloses a method using dimethacrylate having an ester derived from an ethylene glycol derivative such as diethylene glycol dimethacrylate or tetraethylene glycol dimethacrylate as a crosslinking agent in the polymerization of methyl methacrylate and styrene. . Also, JP-A-57-167340 discloses that
In the polymerization of a vinyl monomer having methyl methacrylate as a main component, a method using dimethacrylate having an ester derived from a linear alkanediol such as 1,6-hexanediol dimethacrylate as a crosslinking agent is known. It has been disclosed.

[0003]

In recent years, resin recycling has become an important issue from the viewpoint of preserving the global environment and effectively utilizing resources. However, in addition to the fact that the crosslinked resin obtained using the crosslinker is insoluble and infusible,
It is difficult to decrosslink. For this reason, it has been difficult to effectively treat or reuse after use.

The present invention has been made by paying attention to the problems existing in the above prior art. The object is to provide dimethacrylate having an ester derived from secondary and tertiary alcohol in one molecule, a crosslinking agent containing the same as an active ingredient, a method for producing a crosslinked resin obtained using the same,
And a method for decrosslinking a crosslinked resin.

[0005]

Means for Solving the Problems The present inventors have made intensive studies to achieve the above object, and as a result, have found that a novel and specific dimethacrylate having a specific structure, that is, a secondary and tertiary alcohol in one molecule. It has been found that dimethacrylate having an ester resulting from the above is useful as a crosslinking agent, and that a crosslinked resin obtained by using the same can be easily decrosslinked by heating, thus completing the present invention.

That is, a first invention is 2-methyl-2,4-pentanediol dimethacrylate represented by the following formula (1).

[0007]

Embedded image

[0008] A second aspect of the present invention is directed to the 2-methyl-form of the first aspect.
It is a crosslinking agent containing 2,4-pentanediol dimethacrylate as an active ingredient. The third invention is a crosslinked resin obtained by radical polymerization of a vinyl monomer and the 2-methyl-2,4-pentanediol dimethacrylate of the first invention.
The fourth invention provides the crosslinked resin according to the third invention in an amount of 180 to 300.
A decrosslinking method characterized by heating at a temperature of ° C.

[0009]

Embodiments of the present invention will be described below in detail. 2-Methyl-2,4 of the first invention
-Pentanediol dimethacrylate (hereinafter HGDM)
Abbreviated as A. ) Can be produced according to a conventional general method for producing methacrylate.

For example, it can be obtained by subjecting methacrylic acid chloride and 2-methyl-2,4-pentanediol to an esterification reaction in the presence of a base. Bases used in the esterification reaction include tertiary amines and inorganic bases. Specific examples include, for example, triethylamine, tripropylamine, N, N-diisopropylethylamine, tributylamine, trioctylamine, pyridine, 4-dimethylaminopyridine, 4-pyrrolidinopyridine, sodium hydroxide, potassium hydroxide,
Sodium carbonate, sodium bicarbonate, potassium carbonate,
Potassium hydrogen carbonate and the like can be mentioned. Among these, highly reactive triethylamine, tripropylamine and tributylamine are preferred.

The esterification reaction is usually performed in an organic solvent. For example, methylene chloride, halogen solvents such as chloroform, benzene, toluene, ethylbenzene, aromatic hydrocarbon solvents such as xylene, pentane, hexane, heptane, octane, nonane, decane, 3-methylpentane, 2-hexene, Aliphatic hydrocarbon solvents such as cyclohexane, petroleum naphtha, mineral spirits and Shellsol (manufactured by Shell Chemical), ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone, and ester solvents such as ethyl acetate and butyl acetate , Diethyl ether, dioxane, ether solvents such as tetrahydrofuran, acetonitrile, dimethyl sulfoxide, N, N-dimethylformamide and the like.

The temperature of the esterification reaction is usually from -10 to 8
0 ° C., preferably 0-60 ° C. If the temperature is lower than −10 ° C., the reaction does not proceed sufficiently, and if the temperature is higher than 80 ° C., a side reaction such as a polymerization reaction tends to occur easily.

The above esterification reaction may be carried out in the presence of a polymerization inhibitor such as hydroquinone and methoxyphenol.

The purification method after the completion of the reaction varies depending on the solvent and the base used and is not particularly limited.
It can be purified by acid washing, alkaline washing, distillation, silica gel column or the like.

The cross-linking agent of the second invention contains HGDMA as an active ingredient, and can be used as it is or as an organic solvent which can be used in an esterification reaction, for example, a halogen-based solvent such as methylene chloride or benzene. Such as an aromatic hydrocarbon solvent, an aliphatic hydrocarbon solvent such as pentane, a ketone solvent such as acetone, an ester solvent such as ethyl acetate, or an ether solvent such as diethyl ether. be able to.

HGDMA acts effectively as a cross-linking agent because two vinyl groups of the HGDMA are subjected to radical addition attack to form polymer structural units on both vinyl groups. For example, by performing radical polymerization of a vinyl monomer in the presence of HGDMA,
The vinyl monomer and HGDMA can be copolymerized to form a crosslinked structure. Therefore, it can be suitably used for the purpose of forming a crosslinked structure by a radical reaction.

Examples of the vinyl monomer include styrene monomers such as styrene, α-methylstyrene, vinyltoluene, and chlorostyrene; acrylic acid, methacrylic acid, fumaric acid, maleic anhydride, itaconic acid, and anhydride. Itaconic acid, bicyclo (2,2,1) -5-heptene-2,
Unsaturated carboxylic acids such as 3-dicarboxylic acid, acid anhydrides and metal salts thereof, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, octyl acrylate, octyl methacrylate, lauryl Acrylate, lauryl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2
-Hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, fumaric acid ester, unsaturated carboxylic acid ester such as maleic acid ester, vinyl acetate,
Vinyl esters such as vinyl propionate, vinyl caproate, vinyl caprylate, vinyl laurate and vinyl stearate; unsaturated glycidyl group-containing monomers such as glycidyl acrylate, glycidyl methacrylate, and monoglycidyl itaconate; acrylonitrile Acrylamide, N-phenylmaleimide, vinyl chloride, vinylidene chloride and the like. These vinyl monomers are
One type or two or more types may be used in appropriate combination. Preferred vinyl monomers include styrene, methyl acrylate, methyl methacrylate, butyl acrylate, butyl methacrylate, which are easily copolymerized with HGDMA.
Examples include 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate.

The HGDMA of the present invention can also be used as a crosslinking aid for accelerating a crosslinking reaction when crosslinking a resin or rubber using a radical generator such as an organic peroxide. The crosslinking agent of the present invention includes such a use as a crosslinking aid. Examples of resins and rubbers that can be used as a crosslinking aid include, for example, natural rubber, styrene butadiene rubber, butadiene rubber, isoprene rubber, acrylonitrile butadiene rubber, acrylonitrile butadiene styrene rubber, silicone rubber, hydrogenated acrylonitrile butadiene rubber, fluorine rubber, acrylic Rubber, urethane rubber, polyethylene, ethylene propylene copolymer, ethylene butene copolymer, ethylene pentene copolymer, ethylene vinyl acetate copolymer, ethylene propylene diene copolymer, chlorinated polyethylene, chlorosulfonated polyethylene, ethylene ethyl acrylate copolymer, ethylene methyl methacrylate copolymer, ethylene glycidyl Methacrylate copolymer, ethylene acrylonitrile copolymer and the like. . As the crosslinking method, a known method can be used as it is.

The cross-linked resin of the third invention is a cross-linked resin in which, when radical-polymerizing a vinyl monomer and a cross-linking agent, the cross-linking agent is 2-methyl-2,4-pentanediol dimethacrylate. As the vinyl monomer, the same one as described above is used.

The amount of the crosslinking agent varies depending on the desired degree of crosslinking, but is usually 0.5 to 100 parts by weight, preferably 1 to 80 parts by weight, per 100 parts by weight of the vinyl monomer. If the amount is less than 0.5 part by weight, the crosslinking does not proceed effectively. On the other hand, if it exceeds 100 parts by weight, physical properties such as strength of the crosslinked resin tend to decrease.

As means for radical polymerization, for example,
Initiation means by heat or light in the presence of a radical generator, initiation means using a redox mechanism, initiation means by radiation, and the like. Among these, it is preferable in that the means for initiating by heat in the presence of the radical generator can be relatively easily performed. Examples of the radical generator include dialkyl peroxides such as di-t-butyl peroxide, di-t-hexyl peroxide, and dicumyl peroxide;
1,1-bis (t-butylperoxy) cyclohexane, 1,1-bis (t-butylperoxy) -3,3,3
5-trimethylcyclohexane, 2,2-bis (4,4
Peroxyketals such as -di-t-butylperoxycyclohexyl) propane; t-butylperoxybenzoate, t-hexylperoxybenzoate, t-
Butylperoxyacetate, t-butylperoxylaurate, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxy-2-ethylhexanoate, t-hexylperoxy-2-ethylhexanoate , T-butyl peroxypivalate,
Peroxyesters such as t-hexylperoxypivalate, t-butylperoxyneodecanoate, t-hexylperoxyneodecanoate, cumylperoxyneodecanoate; t-butylperoxyisopropyl monocarbonate, t-hexylperoxy Monoperoxycarbonates such as isopropyl monocarbonate and t-butylperoxy-2-ethylhexyl monocarbonate; diacyl peroxides such as benzoyl peroxide, lauroyl peroxide and 3,5,5-trimethylhexanoyl peroxide; di-n-propylperoxydioxide Peroxydicarbonates such as carbonate, diisopropylperoxydicarbonate and di-2-ethylhexylperoxydicarbonate; 2,
2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (2,4-dimethyl-4-methoxyvaleronitrile), 1,1 ′ Azo compounds such as -azobis (cyclohexanecarbonitrile) and 2,2'-azobis (2,4,4-trimethylpentane).

The amount of the radical generator varies depending on the vinyl monomer used, the polymerization temperature and the like, but is usually 0.001 to 10 parts by weight, preferably 0.01 to 5 parts by weight, per 100 parts of the monomer. Parts by weight.

The polymerization temperature varies depending on the polymerization initiation means.
Usually, it is 0 to 150 ° C, preferably 20 to 140 ° C.

In order to adjust the degree of polymerization and the rate of polymerization of the crosslinked resin, for example, n-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, 2-
Ethylhexyl-β-mercaptopropionate, α-
A chain transfer agent such as methylstyrene dimer can be used.

As the polymerization method, for example, known methods such as bulk polymerization, solution polymerization, suspension polymerization and emulsion polymerization can be applied. A cast polymerization method in which a syrup containing the polymer in a vinyl monomer is prepared, and the syrup is injected into a mold and polymerized, is also possible. At that time, glass fiber,
Reinforcing materials such as vinylon fiber and carbon fiber, calcium carbonate,
Fillers such as aluminum hydroxide and clay, release agents, ultraviolet absorbers, coloring agents, stabilizers, flame retardants and the like may be added.

The method for decrosslinking a crosslinked resin according to the fourth invention is characterized in that the crosslinked resin according to the third invention is usually heated at a temperature of 180 to 300 ° C.

By heating in the above-mentioned temperature range, the cross-linking in the cross-linked resin can be selectively broken, and it can be converted to a thermoplastic resin which is soluble in a solvent. A more preferred heating temperature is 200 to 280 ° C. If the heating temperature is lower than 180 ° C., there is a tendency that breakage of cross-linking does not occur or progress does not proceed efficiently. Also, 30
If the temperature exceeds 0 ° C., the resin body tends to be easily decomposed.

The heating method is not particularly limited, and examples thereof include heating in an oven, heating under pressure by a press, and heating while kneading. It is also possible to partially heat the crosslinked resin.

[0029]

Next, the present invention will be described more specifically with reference to examples and comparative examples. In addition, the part and% in each example show a weight part and weight% unless there is particular notice. Abbreviations in each example indicate the following compounds. HGDMA: 2-methyl-2,4-pentanediol dimethacrylate DEGDMA: diethylene glycol dimethacrylate MMA: methyl methacrylate

Example 1 In a 200 cc four-necked flask equipped with a stirrer and a thermometer, 5 g of 2-methyl-2,4-pentanediol, 12.9 g of triethylamine and 50 ml of methylene chloride were placed, and a water bath was stirred. At 15 ° C. Thereto, 13.3 g of methacrylic acid chloride was added dropwise over 15 minutes. After completion of the dropwise addition, the mixture was stirred at a temperature of 15 to 20 ° C for 4
Continued for hours. After completion of the reaction, the solution was separated by adding water, and the organic layer was washed with a 5% aqueous sodium hydroxide solution, 5% aqueous hydrochloric acid and water in this order. After dehydrating the organic layer with anhydrous magnesium sulfate, the solvent was distilled off under reduced pressure to obtain 9.75 g of a crude product. This was purified by a silica gel column to obtain a colorless and transparent liquid. Its infrared absorption spectrum (IR) and nuclear magnetic resonance spectrum ⁽¹ H-NMR)
Is measured, the obtained compound is represented by the following formula (2)
HGDMA was confirmed.

[0031]

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IR: 1714 cm ^-1 (C = O expansion and contraction),
1637 cm ^-1 (C = C stretching) ¹ H-NMR (CDCl ₃ ): (a): δ = 1.12 (d, 3H, J = 6.2 Hz) (b): δ = 1.36 (s, 3H) (c): δ = 1.38 (s, 3H) (d): δ = 1.72 (s, 3H) (e): δ = 1.77 (s, 3H) (f): δ = 1.94 (dd, 1H, J = 14.7H
z, 3.1 Hz) (g): δ = 2.20 (dd, 1H, J = 15.0H)
z, 8.8 Hz) (h): δ = 5.11 (m, 1H) (o): δ = 5.33 (s, 1H) (p): δ = 5.39 (s, 1H) (q ): Δ = 5.85 (s, 1H) (r): δ = 5.92 (s, 1H)

Example 2 A mixed solution containing 95 parts of styrene, 5 parts of HGDMA and 0.005 mol / liter of t-butylperoxybenzoate as a polymerization initiator with respect to styrene was placed in a glass ampoule, replaced with nitrogen, and sealed. It was immersed in a thermostat at 120 ° C. and polymerized for 5 hours. The polymer was then heated in an oven at 250 ° C. for 30 minutes. Approximately 0.1 g of each sample was taken from the polymer before and after heating, and immersed in 10 ml of benzene at room temperature overnight to examine the solubility. As a result, the sample before heating only swelled and did not dissolve in benzene. On the other hand, the sample after heating was completely dissolved in benzene. The molecular weight of the heated sample was measured by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent using a standard polystyrene calibration curve. As a result, the weight average molecular weight was 317,000.

Comparative Example 1 Polymerization was carried out in the same manner as in Example 2 except that HGDMA was not used. As a result of examining the solubility of the obtained polymer in benzene according to Example 2, the polymer was completely dissolved in benzene. The weight average molecular weight determined by GPC is 31.
It was 70,000.

Comparative Example 2 Polymerization was carried out in the same manner as in Example 2 except that DEGDMA was used instead of HGDMA. Next, the polymer was heated in an oven at 250 ° C. for 30 minutes, and the solubility was examined according to the method of Example 2. As a result, both the sample before and after heating swelled but did not dissolve in benzene.

Example 3 95 parts of MMA, 5 parts of HGDMA, 0.005 mol / l of lauroyl peroxide as a polymerization initiator for MMA and 0.3% of n-dodecylmercaptan as a chain transfer agent for the whole solution (based on the total solution volume) weight%)
Was placed in a glass ampoule, replaced with nitrogen, sealed, immersed in a constant temperature bath at 70 ° C., and polymerized for 5 hours. The polymer was then heated in an oven at 250 ° C. for 30 minutes. Approximately 0.1 g of each sample was taken from the polymer before and after heating, and immersed in 10 ml of benzene at 40 ° C. overnight to examine the solubility. As a result, the sample before heating only swelled and did not dissolve in benzene. On the other hand, the sample after heating was completely dissolved in benzene. The molecular weight of the heated sample was measured by GPC. As a result, the weight average molecular weight in terms of polystyrene was 102,000.

Comparative Example 3 Polymerization was carried out in the same manner as in Example 3 except that HGDMA was not used. The obtained polymer was completely dissolved in benzene. The polystyrene equivalent weight average molecular weight determined by GPC was 104,000.

Comparative Example 4 Polymerization was carried out in the same manner as in Example 3 except that DEGDMA was used instead of HGDMA. Next, the polymer was heated in an oven at 250 ° C. for 30 minutes, and the solubility was examined according to the method of Example 3. As a result, both the sample before and after heating swelled but did not dissolve in benzene.

From the results of the solubility of the polymer before heating in Example 2 and Comparative Example 2, HGDMA of the present invention is
It was found that, similarly to DMA, during styrene polymerization, it effectively functions as a crosslinking agent and easily gives a solvent-insoluble crosslinked product (gel). On the other hand, from the comparison of the solubility results for the polymer after heating in Example 2 and Comparative Example 2, the crosslinked product obtained using DEGDMA was insoluble in the solvent even when heated, but was obtained using HGDMA. It was found that the crosslinked product became soluble in the solvent when heated. The product obtained after the heating, as is apparent from the GPC measurement results of Example 2 and Comparative Example 1, has almost the same molecular weight as polystyrene obtained without using a crosslinking agent, and is obtained using HGDMA. It was found that by heating the cross-linked product, only the cross-linking site was selectively cut and converted into a linear polymer (thermoplastic resin). As is clear from the comparison between Example 3 and Comparative Examples 3 and 4, the same fact as in the case of styrene was observed when MMA was used as a monomer.

[0040]

As described in detail above, the HGDM of the present invention
A is a novel compound useful as a crosslinking agent. In addition, a crosslinked resin can be easily obtained using it. The crosslinked resin obtained by the polymerization can be selectively crosslinked by simply heating, and can be converted into a solvent-soluble thermoplastic resin which can be easily molded. From these points, the crosslinked resin is effectively treated,
The value of the present invention is extremely large in that it can be processed or reused.

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 4J100 AB02P AB03P AB04P AB08P AC03P AC04P AG02P AG04P AJ02P AJ08P AJ09P AK31P AK32P AL03P AL04P AL08P AL10P AL14P AL62Q AM02P AM15P AM48P BA03P CA04 FA03

Claims (4)

[Claims] 1. 2-methyl- represented by the following formula (1)
2,4-pentanediol dimethacrylate. Embedded image 2. A crosslinking agent comprising the 2-methyl-2,4-pentanediol dimethacrylate according to claim 1 as an active ingredient. 3. A crosslinked resin obtained by radical polymerization of a vinyl monomer and the 2-methyl-2,4-pentanediol dimethacrylate according to claim 1. 4. The crosslinked resin according to claim 3, wherein
A decrosslinking method characterized by heating at a temperature of 0 ° C.