JP5127549B2 - Method for modifying polymer compound, low shrinkage material for plastic, and method for using polymer compound - Google Patents

Description

  The present invention relates to a method for modifying a polymer compound, a low shrinkage material for plastics, and a method for using the polymer compound.

  Conventionally, most plastic wastes made from thermosetting resins have been disposed of in landfills. However, there is a problem that it is difficult to secure a land for landfill, and there is a problem that the ground becomes unstable after landfill, and it is desired to recycle plastic waste made from this thermosetting resin.

Therefore, when the present thermosetting resin obtained by cross-linking a copolymer of polyhydric alcohol and acid with a cross-linking material is decomposed below the thermal decomposition temperature of the plastic using subcritical water, it is re-used as a raw material for the thermosetting resin. A method has been proposed in which a styrene-fumaric acid copolymer, which is a copolymer of a crosslinked part and an acid, can be obtained together with a usable monomer. The carboxylic acid group portion contained in the structure of the styrene-fumaric acid copolymer obtained by this method is subjected to a modification reaction to obtain a carboxylic acid anhydride or a carboxylic acid ester, which is a raw material for the thermosetting resin. By solubilizing in one styrene, it can be used as a low shrinkage agent that reduces the shrinkage of a plastic molded product that occurs during molding of a thermosetting resin (see, for example, Patent Documents 1-4). .
International Publication WO2005 / 092962 Pamphlet JP 2005-336322 A JP 2006-36938 A JP 2007-31546 A

  However, in the modification reaction of a polymer compound having a carboxylic acid group in the side chain such as the styrene-fumaric acid copolymer, the reaction is unstable and the yield of the target substance is low or the reactivity is low. There are still some points to be improved, such as the need to carry out the reaction at a high temperature for a long time, and it is actually desired to carry out the reforming reaction in a relatively short time.

  The present invention has been made in view of the circumstances as described above, and a method for modifying a polymer compound capable of efficiently modifying a polymer compound having a carboxylic acid group in a side chain in a relatively short time, for plastics It is an object of the present invention to provide a method for using a low shrinkage material and a polymer compound.

  The present invention is characterized by the following in order to solve the above problems.

  First, as a method for modifying a polymer compound, a polymer compound having a carboxylic acid group in a side chain is subjected to dehydration reaction of alcohol under microwave irradiation to obtain a modified product of the polymer compound. And

  Second, in the first method for modifying a polymer compound, the polymer compound having a carboxylic acid group in the side chain is a styrene-fumaric acid copolymer, and the alcohol has 3 or more carbon atoms. It is characterized by being a monoalcohol.

  Third, in the second method for modifying a polymer compound, the styrene-fumaric acid copolymer is obtained by subcritical water decomposition of an unsaturated polyester resin.

  Fourth, in the first polymer compound modification method, the polymer compound having a carboxylic acid group in the side chain is polymethacrylic acid.

  Fifth, in the fourth method for modifying a polymer compound, polymethacrylic acid is obtained by subcritical water decomposition of an acrylic resin.

  Sixth, adding a solvent that has a specific gravity smaller than that of water, phase-separates from water, and generates an azeotropic compound to the reaction system of any one of the first to fifth polymer compound modification methods. It is characterized by.

  Seventh, in any one of the first to sixth methods for modifying a polymer compound, an inert gas is introduced into the reaction solution.

  Eighth, adding any one of sulfuric acid, paratoluenesulfonic acid and diazacycloundecene as a catalyst to the reaction system of any one of the first to seventh polymer compound reforming methods It is characterized by.

  Ninth, the low-shrinkage agent for plastics contains a modified product obtained by any one of the first to eighth methods for modifying a polymer compound.

  Tenth, as a method of using a polymer compound, the modified product obtained by any one of the first to eighth polymer compound modification methods is blended in a thermosetting resin.

  According to the first invention, the polymer compound having a carboxylic acid group in the side chain is subjected to dehydration reaction (esterification reaction) of alcohol under microwave irradiation, and the esterified product of the polymer compound is used as a modified product. obtain. Conventionally, in order to obtain such a modified product, treatment at a high temperature for a long time is required. However, in the present invention, the modified product can be obtained with a relatively short treatment and in a high yield. In addition, this modified product is soluble in styrene, which is one of the raw materials for thermosetting resins, and can be used as a low shrinkage agent that reduces the shrinkage of plastic molded products that occur during the molding of thermosetting resins. .

  According to the second invention, the polymer compound having a carboxylic acid group in the side chain is a styrene-fumaric acid copolymer, and the alcohol is a monoalcohol having 3 or more carbon atoms. A modified styrene-fumaric acid copolymer is obtained as a material. This is soluble in styrene, which is one of the raw materials for thermosetting resins, and can be used as a low shrinkage agent for plastic molded products.

  According to the third invention, since the styrene-fumaric acid copolymer is obtained by subcritical water decomposition of the unsaturated polyester resin, plastic waste made of the unsaturated polyester resin can be recycled. .

  According to the fourth invention, when the polymer compound having a carboxylic acid group in the side chain is polymethacrylic acid, a polymethacrylic acid ester as a modified product is obtained. This is soluble in styrene, which is one of the raw materials for thermosetting resins, and can be used as a low shrinkage agent for plastic molded products.

  According to the fifth aspect of the invention, polymethacrylic acid is obtained by subcritical water decomposition of an acrylic resin, so that plastic waste made of the acrylic resin can be recycled.

  According to the sixth invention, a solvent that has a specific gravity smaller than that of water, phase-separates from water, and generates an azeotropic compound in the reaction system of any one of the first to fifth polymer compound reforming methods. By adding, water generated in the esterification reaction between the polymer having a carboxylic acid group in the side chain and the alcohol is efficiently removed out of the system. Since the esterification reaction is an equilibrium reaction, when water is removed from the reaction system, the reaction proceeds in a direction in which a reformed product is generated, and the yield of the reformed product can be increased.

  According to the seventh invention, in the method for modifying any one of the first to sixth polymer compounds, the amount of dissolved oxygen in the reaction solution is reduced by introducing an inert gas into the reaction solution. Thus, coloring of the modified product due to oxidation during the esterification reaction can be suppressed.

  According to the eighth invention, any one of sulfuric acid, paratoluenesulfonic acid and diazacycloundecene is used as a catalyst in the reaction system of any one of the first to seventh polymer compound modification methods. By adding, the reaction efficiency can be further increased and a reformed product can be obtained in a high yield.

  According to the ninth invention, by containing the modified product obtained by any one of the first to eighth polymer compound modification methods, molding a thermosetting resin as a low shrinkage agent for plastics. It is possible to effectively reduce the shrinkage of the plastic molded product that sometimes occurs.

  According to the tenth invention, a side chain has a carboxylic acid group by blending the modified product obtained by any one of the first to eighth polymer compound modification methods with a thermosetting resin. The polymer compound can be used as a low shrinkage agent for plastics that effectively reduces shrinkage of a plastic molded product that occurs during molding of a thermosetting resin.

  In the present invention, a polymer compound having a carboxylic acid group in the side chain is subjected to a dehydration reaction (hereinafter also referred to as an esterification reaction) to obtain an esterified product of the polymer compound as a modified product. The most characteristic feature of the present invention is that the esterification reaction is performed under microwave irradiation. Hereinafter, embodiments of the present invention will be described in detail.

  The microwave used in the present embodiment is generally a radio wave (electromagnetic wave) having a frequency of 1 GHz or more and 3 THz or less, for example, a polymer compound having a carboxylic acid group in the side chain using a magnetron as a microwave generation source, and The alcohol reaction system is irradiated. When irradiated with microwaves, for example, the molecules constituting the polymer compound and alcohol in the reaction system vibrate according to the frequency of the microwaves, and frictional heat is generated between the molecules to generate heat and raise the temperature, The reaction system is heated. Conventionally, the reaction system was heated with an electric heater or the like. However, since most of the heat energy is dissipated to the outside, it must be processed at a high temperature for a long time, leading to an increase in heat energy consumption and poor thermal efficiency. It was. In this embodiment, since only the reaction system of the polymer compound and alcohol can be selectively heated in a short time without consuming heat energy to the outside, the esterification reaction can be effectively promoted. it can. Therefore, the modified product can be obtained in a high yield with a short reaction time.

  The frequency of the microwave used in the present embodiment is not particularly limited, but is preferably 1 GHz to 30 GHz, and more preferably 2.4 GHz to 2.5 GHz where a microwave generator can be obtained at low cost. In particular, 2.45 GHz is preferable from the viewpoint of heating efficiency. The microwave irradiation time varies depending on the frequency of the microwave and the amount of the polymer compound and alcohol in the reaction system. In this embodiment, the polymer is compared with the conventional method in which the reaction system is heated with an electric heater or the like. Since only the reaction system of the compound and the alcohol can be selectively and effectively heated, for example, conventionally, the treatment was performed with an electric heater for more than 15 hours. However, in this embodiment, microwaves are applied to the reaction system. The modified product can be obtained in a high yield by irradiation within 3 hours, in some cases within 1 hour, and further for about 30 minutes. In the examples described later, the modified product is obtained in a high yield by irradiating with microwaves under conditions of 2.45 GHz and 150 W for 30 minutes.

  Examples of the polymer compound having a carboxylic acid group in the side chain to be modified in this embodiment include a styrene-fumaric acid copolymer, polymethacrylic acid, polyacrylic acid, and vinyl polycarboxylate. Among them, as will be described later, it is preferable to use a styrene-fumaric acid copolymer or polymethacrylic acid for recycling plastic waste.

  The styrene-fumaric acid copolymer can be obtained, for example, by subcritical water decomposition of an unsaturated polyester resin in which a copolymer of a polyhydric alcohol and an unsaturated polybasic acid is crosslinked with a crosslinking agent. Specific examples of the polyhydric alcohol that is a raw material for the unsaturated polyester resin include glycols such as ethylene glycol, propylene glycol, neopentyl glycol, diethylene glycol, and dipropylene glycol. These can be used alone or in combination of two or more. Specific examples of the polybasic acid that is a raw material of the unsaturated polyester resin include aliphatic unsaturated dibasic acids such as maleic anhydride, maleic acid, and fumaric acid. These can be used alone or in combination of two or more. A saturated polybasic acid such as phthalic anhydride may be used in combination with the unsaturated polybasic acid. Examples of the crosslinking agent for crosslinking a copolymer composed of a polyhydric alcohol and an unsaturated polybasic acid include, but are not limited to, polymerizable vinyl monomers such as styrene and methyl methacrylate.

  Polymethacrylic acid can be obtained by, for example, subcritical water decomposition of an acrylic resin. The acrylic resin is a thermoplastic resin obtained by two-dimensionally polymerizing a methacrylic ester or a thermosetting resin obtained by crosslinking a methacrylic ester with a crosslinking agent. Examples of the methacrylic acid ester that is a raw material for the acrylic resin include, but are not limited to, methyl methacrylate and butyl methacrylate. Examples of the crosslinking agent that crosslinks the methacrylic acid ester include glycols such as ethylene glycol, propylene glycol, diethylene glycol, and dipropylene glycol, but are not limited thereto.

  The unsaturated polyester resin and acrylic resin described above are used, for example, as plastic molded products such as bathroom units and system kitchens. As described above, in the present embodiment, wastes from these plastic molded products are subcritical water decomposed. Thus, a styrene-fumaric acid copolymer and polymethacrylic acid are produced, and these are modified so as to be reusable, thereby recycling plastic molding waste. Here, subcritical water decomposition refers to, for example, adding water in an alkaline state to a plastic such as an unsaturated polyester resin or an acrylic resin, and raising the temperature and pressure to bring the water to a critical point (critical temperature 374.4 ° C., critical pressure 22 .1 MPa) refers to decomposing plastic in a subcritical state below. Styrene-fumaric acid copolymer and polymethacrylic acid, for example, after solid-liquid separation of a decomposition solution obtained by subcritical water decomposition of unsaturated polyester resin or acrylic resin, respectively, sulfuric acid, hydrochloric acid, nitric acid It can obtain by adding the acid etc. and heating and drying the filtrate isolate | separated by filtration etc.

  The blending ratio of the unsaturated polyester resin or acrylic resin and the alkaline water is not particularly limited. For example, the amount of alkaline water added is 100 to 500 parts by mass with respect to 100 parts by mass of the plastic. It is preferable to make it into a range. When the blending amount of alkaline water is less than 100 parts by mass, it becomes difficult to stably decompose the plastic, and when it exceeds 500 parts by mass, the cost of water treatment after decomposition becomes high. It is not preferable.

  The alkali used for the water in the alkaline state is desirably water-soluble and relatively inexpensive, and examples thereof include sodium hydroxide and potassium hydroxide. The concentration of the alkali is preferably 0.08N to 2N from the viewpoint of plastic decomposition efficiency.

  About the decomposition temperature which subcritical water-decomposes plastics, such as an unsaturated polyester resin and an acrylic resin, with alkaline water, the range of 180-270 degreeC is preferable. If the decomposition temperature is less than 180 ° C, it takes a long time to decompose, and the processing cost may be increased. If the decomposition temperature exceeds 270 ° C, the influence of thermal decomposition becomes large. This is not preferable because the coalescence may be decomposed and cannot be recovered as a copolymer of a cross-linked portion and an acid as a solid. The decomposition time and decomposition pressure are not particularly limited, but in the above decomposition temperature range, the range of 1 to 4 hours and 2 to 15 MPa is preferable.

  In the present embodiment, specific examples of the alcohol used for the esterification reaction of the polymer compound having a carboxylic acid group in the side chain include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, and 2-butanol. 1-pentanol, 2-pentanol, 1-hexanol, 2-hexanol, 1-heptanol, 2-heptanol, 1-octanol, 2-octanol, 1-decanol, 2-decanol, 1-dodecanol and the like. . In particular, when the polymer compound having a carboxylic acid group in the side chain is a styrene-fumaric acid copolymer, it is preferable to use a monoalcohol having 3 or more carbon atoms as the alcohol. As a result, the modified styrene-fumaric acid copolymer as a modified product obtained after the modification of the styrene-fumaric acid copolymer is used as a crosslinking agent for thermosetting resins such as unsaturated polyester resins, as will be described later. Therefore, it can be effectively used as a low shrinkage agent for plastic molded products.

  In this embodiment, a solvent that has a specific gravity smaller than that of water, phase-separates with water, and generates an azeotropic compound may be added to the reaction system of the polymer compound having a carboxylic acid group in the side chain and the alcohol. . For example, a fixed amount of a solvent such as benzene or toluene is continuously added to the reaction system by liquid feeding using a pump or the like, or a Dean-Stark apparatus. As a result, water generated in the esterification reaction between the polymer having a carboxylic acid group in the side chain and the alcohol is efficiently removed out of the system. Since the esterification reaction is an equilibrium reaction, when water is removed from the reaction system, the reaction proceeds in a direction in which a reformed product is generated, and the yield of the reformed product can be increased.

  In the present embodiment, an inert gas such as nitrogen or argon can be introduced into a reaction solution of a polymer having a carboxylic acid group in the side chain and an alcohol by a method such as bubbling. Thereby, the amount of dissolved oxygen in the reaction solution can be reduced, and coloring of the modified product due to oxidation during the esterification reaction can be suppressed. Therefore, when this modified product is used, for example, as a low-shrinkage agent for plastics, it is possible to prevent coloring of the plastic molded product caused by the modified product, and to replace a commercially available low-shrinkage agent without impairing the appearance of the product. Can be used as a product.

  Furthermore, in this embodiment, in order to increase the reaction efficiency between the polymer compound having a carboxylic acid group in the side chain and the alcohol to obtain a modified product in a high yield, a catalyst is added to the reaction system, It is preferred to carry out the esterification reaction under irradiation. Specific examples of such a catalyst include acidic catalysts such as sulfuric acid, paratoluenesulfonic acid and acidic zeolite, diazacycloundecene (DBU), montmorillonite KSF and the like. Of these, sulfuric acid, paratoluenesulfonic acid, and DBU, which can obtain a modified product with high reaction efficiency and high yield and are easily available, are preferred, and sulfuric acid can be mentioned as a suitable catalyst.

  As described above, the modified product of the polymer compound as an esterified product obtained by the esterification reaction of a polymer compound having a carboxylic acid group in the side chain and an alcohol is a plastic molding generated at the time of molding a thermosetting resin. Effectively used as a low-shrinkage agent to reduce product shrinkage. Conventionally, polystyrene is used as a low shrinkage agent in thermosetting resins such as unsaturated polyester resins, but even if a part or all of the polystyrene is replaced with the modified product in this embodiment, it is as low as polystyrene. Shrink performance can be achieved. In particular, styrene-fumaric acid copolymers and modified products of polymethacrylic acid (for example, modified styrene-fumaric acid copolymers and polymethacrylic acid esters) are used as crosslinking agents for thermosetting resins such as unsaturated polyester resins. Since it is soluble in styrene, it can be suitably used as a low shrinkage agent without impairing the mechanical properties and appearance of the plastic molded product.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to said embodiment at all. Next, the present invention will be specifically described with reference to examples.

<Examples 1-5, Comparative Examples 1-2>
Under the conditions shown in Table 1, a polymer compound having a carboxylic acid group in the side chain is subjected to dehydration reaction (esterification reaction) of alcohol under microwave irradiation to produce a modified product (esterification product) of the polymer compound. The yield was determined. Next, a plastic molded product was produced using the obtained modified product, and its low shrinkage was evaluated.

The yield was obtained from the following formula.
Yield (%) = (Weight of esterified product) / {(Weight of polymer compound having carboxylic acid group in side chain used for esterification reaction) × F} × 100
F in the formula represents the rate of weight increase when all the carboxylic acid groups in the polymer compound having a carboxylic acid group in the side chain used for the esterification reaction are reacted with alcohol to be esterified. For F, the amount of carboxylic acid groups contained in the unit weight of the polymer compound having a carboxylic acid group in the side chain such as styrene-fumaric acid copolymer or polymethacrylic acid is determined by titration or NMR. If it is obtained in advance by chemical analysis and the number of carboxylic acid groups per unit weight is known, F can be obtained. For example, a styrene-fumaric acid copolymer obtained by subcritical water decomposition of an FRP bath has a ratio of styrene acid: fumaric acid of about 2: 1. Therefore, when octanol is reacted with this, the two carboxylic acid groups of fumaric acid react with two molecules of octanol, and two molecules of water are obtained, and in this case, F becomes about 1.7.

Moreover, the plastic molded product produced using the obtained modified product and its low shrinkage evaluation are as follows.
<Production of plastic molded products>
Polyhydric glycols such as propylene glycol, neopentyl glycol, dipropylene glycol and unsaturated organic acid maleic anhydride, which are mixed with glycols in an equivalent amount, and styrene as a crosslinking agent, and thermosetting 100 parts by weight of the resin, 8 parts by weight of polystyrene as a low shrinkage agent, 8 parts by weight of the resulting modified product, 165 parts by weight of calcium carbonate, and 90 parts by weight of glass fiber are placed in a mold and heated and cured. A plastic molded product was produced.
<Evaluation of low shrinkage>
For evaluation of low shrinkage, the amount of shrinkage (dimensional change) of the cured product (plastic molded product) relative to the size of the mold used for the production of the plastic molded product was measured, and the shrinkage rate was obtained. When the shrinkage rate was less than 2.5%, it was evaluated as “◯”, when it was in the range of 2.5% to 3.0%, “Δ”, and when it exceeded 3.0%, it was evaluated as “x”.

  The results are shown in Table 1.

  In Examples 1 to 5, the polymer compound having a carboxylic acid group in the side chain was subjected to a dehydration reaction of alcohol under microwave irradiation. %), It was confirmed that a modified product was obtained. On the other hand, in Comparative Examples 1 and 2 where microwaves were not irradiated, it was confirmed that it was necessary to heat the reaction system at a high temperature for more than 15 hours with an electric heater. Moreover, when the Example which compared the raw material, alcohol, and catalyst which originated the polymer compound which has a carboxylic acid group, the polymer compound which has a carboxylic acid group on the same conditions, and a comparative example (Example 4 and Comparative Example 1 and Comparison between Example 5 and Comparative Example 2), Example 4 and Example 5 confirmed that the modified product was obtained in a yield higher than that of Comparative Example 1 and Comparative Example 2, respectively.

Claims (5)

  A method for modifying a polymer compound, wherein a polymer compound having a carboxylic acid group in a side chain is subjected to dehydration reaction of alcohol under microwave irradiation to obtain a modified product of the polymer compound, wherein the side chain has a carboxylic acid A method for modifying a polymer compound, wherein the polymer compound having a group is a styrene-fumaric acid copolymer, and the alcohol is a monoalcohol having 3 or more carbon atoms.   The method for modifying a polymer compound according to claim 1, wherein the styrene-fumaric acid copolymer is obtained by subcritical water decomposition of an unsaturated polyester resin.   A polymer having a specific gravity smaller than that of water, phase-separated from water, and generating an azeotropic compound, in the reaction system of the method for modifying a polymer compound according to claim 1 or 2. Compound modification method.   The method for modifying a polymer compound according to any one of claims 1 to 3, wherein an inert gas is introduced into the reaction solution.   Addition of any one of sulfuric acid, paratoluenesulfonic acid and diazabicycloundecene as a catalyst to the reaction system of the method for modifying a polymer compound according to any one of claims 1 to 4. A method for modifying a polymer compound.