JPH08151438A - Production of unsaturated polyester resin - Google Patents

Abstract

PURPOSE: To providd a process for producing an unsatd. polyester or polyester resin from a recycled waste PET whereby the glycolysis of the waste PET is carried out smoothly even when the ratio of a glycol used to the waste PET is low and a high-PET-content polyester or polyester resin is obtd. CONSTITUTION: An unsatd. plyester is produced by melting 20-90mol% (in terms of repeating unit content) recycled polyethylene terephthalate, successively adding 80-10mol% glycol to the melt to conduct glycolysis until a homogeneous phase is obtd., adding thereto a required amt. of an α,β-unsatd. polybasic acid or its anhydride, and conducting esterification to a desired conversion. The polyester is compounded with a monomer copolymerizable therewith.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to recycling of polyethylene terephthalate recovered from polyethylene terephthalate bottles and the like, and to a method for producing an unsaturated polyester resin using recovered polyethylene terephthalate as a raw material.

[0002]

2. Description of the Related Art In recent years, there has been a movement to recycle polyethylene terephthalate (hereinafter abbreviated as PET) bottles.
It is said that it is very difficult to recycle to improve the quality, and the cost of a bottle molded from recycled PET is several times higher than that of the PET bottle before recycling, which is not practical.

On the other hand, when a PET bottle is used as a raw material for producing an unsaturated polyester resin, it is possible to use waste PET (PET waist, PET scraps) from which foreign substances are removed as much as possible, and the cost is practical. In some cases, it can be used at a low cost rather than in the case of producing an unsaturated polyester resin using terephthalic acid and ethylene glycol as raw materials. However, in the conventional method, that is, in the method of adding waste PET to glycol and heating to decompose glycol, the use ratio of waste PET is limited to about 30% by weight of the total polyester (excluding monomers).
If it is attempted to use an amount of waste PET larger than this, not only will it take a very long time to dissolve and decompose the glycol, but it may partially heat up and decompose.

[0004]

SUMMARY OF THE INVENTION From the standpoint of promoting the recycling of waste pets, the present invention, in other words, uses glycol in proportion to the proportion of waste PET, even if the proportion of waste pet used in glycol is large. Even if the ratio is relatively small, the waste PET can be smoothly decomposed into glycol and the waste PE
An object of the present invention is to provide a method for producing an unsaturated polyester in which the amount of T used is as large as possible (for example, 30% by weight or more), and a method for producing an unsaturated polyester resin in which a monomer copolymerizable with the unsaturated polyester is blended. And

[0005]

DISCLOSURE OF THE INVENTION The present inventors have made use of waste PET.
As a result of various studies on unsaturated polyester and a method for producing an unsaturated polyester resin that use as much as possible, the waste PET was kept in a molten state and the required amount of glycol was added to it, contrary to the conventional method. Sequentially added to waste P
Glycolysis of ET is performed, and then the required amount of α, β-
It was found that the above object can be achieved by adding an unsaturated polybasic acid or an acid anhydride thereof for esterification, and the present invention could be completed.

That is, in the present invention, 20 to 90 mol% of recovered polyethylene terephthalate is melted (1 mol of the repeating unit), and 80 to 10 mol% of glycol is sequentially added to the melted polyethylene terephthalate to homogenize it. The invention relates to a process for producing an unsaturated polyester characterized in that after the glycol decomposition is carried out until the above condition, a necessary amount of α, β-unsaturated polybasic acid or its acid anhydride is added, and further esterification is carried out up to the necessary stage. .

The present invention also relates to a method for producing an unsaturated polyester resin, characterized in that the unsaturated polyester obtained in the above invention is blended with a monomer copolymerizable therewith.

In the method of the present invention, the molten waste P is initially used.
It was thought that rapid addition of glycol to ET might cause rapid reflux of glycol because the melting temperature of waste PET was high. It was rather surprising that such a phenomenon did not occur at all and the glycol decomposition of the waste PET was performed smoothly.

The present invention will be described in more detail below. The recovered PET used in the present invention is generally a mixture of PET bottles crushed to rice grain size, washed, dried transparent pellets mixed with pellets of each color,
A floppy disk containing iron oxide can also be used.

In the present invention, the recovered PET
Is kept in a molten state at 260 ° C. or higher, preferably 265 to 270 ° C., and glycol is sequentially added thereto to decompose the waste PET by glycol.

The glycol used in the present invention is not always desirable because ethyl glycol causes a problem of compatibility with monomers, but it is not necessary to limit other glycols, for example, propylene glycol,
Dipropylene glycol, diethylene glycol, 1,
2-butanediol, 1,3-butanediol, neopentyl glycol, 2-methylpropanediol-1,
Examples include 3,1,4-cyclohexanedimethanol, 3-methylpentanediol-1,5, octylene glycol, nonamethylene glycol, hydrogenated bisphenol A and the like. These glycols can be used in combination. Glycol, which is a powder at room temperature in the glycol, is melted and added sequentially, but may be dividedly charged as a powder.

Of the above-mentioned glycols, 1,2-butanediol and glycols having a methyl group are preferable because they can improve the compatibility with the monomer copolymerized with the unsaturated polyester. In particular, when 1,2-butanediol is used as glycol, a relatively small amount of 1,2-butanediol is used with respect to the amount of waste PET, and when it is made into an unsaturated polyester resin, it is copolymerized with the unsaturated polyester. It is preferable because the compatibility with the monomer can be kept good and the physical properties of the cured resin, especially the toughness, can be imparted. For example, when 1,2-butanediol is used as the glycol, even if the amount used is 20 mol%, the remaining 80 mol% is waste PET, that is, even if 80 mol% is ethylene glycol as the glycol component, unsaturated polyester and Compatibility with monomers that copolymerize with is guaranteed. The 1,2-butanediol can be used as a purified product or as a crude product containing 10% of monoacetate in and out. It is free to use in combination with other glycols as needed.

When propylene glycol is used as the glycol having a methyl group, in order to ensure the compatibility (for example, a 50% styrene solution; the same applies hereinafter) between the unsaturated polyester and the monomer copolymerized therewith,
When the total glycol used is 100 mol%, 50 mol% or more, preferably 60 mol%, is used, and compatibility can be secured with the monomer to be copolymerized when 40 mol% of ethylene glycol is used. This is particularly suitable when the modifying saturated acid is phthalic acid, isophthalic acid, or terephthalic acid, but with neopentyl glycol, dipropylene glycol or 2-methylpropanediol-1,3, the remaining 80 mol% remains at 80%. Even if mol% is PET, that is, 80 mol% is ethylene glycol as a glycol component, compatibility with the monomer to be copolymerized is guaranteed. Therefore, in order to obtain an unsaturated polyester resin in which the amount of waste PET used is as large as possible, which is the object of the present invention,
Butanediol, glycols with a methyl group, such as neopentyl glycol, dipropylene glycol or 2-methylpropanediol-1,3 are by far the most convenient glycols.

In the present invention, glycol is sequentially added to the waste PET in a molten state. The reason why the glycols are sequentially added is that if all the glycols are added to the melted waste PET all at once, a block of PET is deposited and stirring becomes difficult. Sequential addition of glycol may be continuously added or added dropwise with stirring, or intermittently added or added dropwise.

The usage ratio of waste PET and glycol varies depending on the type of glycol, but the waste PET shown below is used.
Repeating unit

Embedded image 20 to 90 mol% and glycol 80 to 1
0 to 80 mol%, preferably 40 to 80 mol% of glycol and 60 to 2 mol of the repeating unit of waste PET as 1 mol.
It consists of 0 mol%. 80 mol% of glycol used
If the amount is larger, it makes little sense to use the waste PET. When the amount is less than 10 mol%, the crystallinity of the unsaturated polyester produced causes a problem in compatibility with the monomer (styrene).

After the waste PET is decomposed with glycol, the necessary amount of α, β-unsaturated polybasic acid or its acid anhydride is added,
Esterification to the required stage to produce unsaturated polyester. The necessary amount referred to here is approximately equimolar to the sequentially added glycol, that is, α, β-in the range of 10 to 80 mol%.
This means adding an unsaturated polybasic acid or its acid anhydride.

As the α, β-unsaturated polybasic acid or its acid anhydride used, maleic acid, maleic anhydride,
Examples include fumaric acid. The α, β-unsaturated polybasic acid or its acid anhydride may be used in combination with a saturated polybasic acid or its acid anhydride, if necessary. Examples of the saturated polybasic acid or its acid anhydride include phthalic anhydride, isophthalic acid, terephthalic acid and terephthalic acid dimethyl ester having a benzene nucleus.

The esterification is carried out according to a conventional method in an inert gas stream at a temperature of 160 to 230 ° C., and in some cases, under reduced pressure, the esterification is carried out to the required stage. The necessary stage here means that the acid value of the unsaturated polyester is 100 or less,
It preferably means esterification up to 30 to 70. The acid value of the unsaturated polyester is appropriately determined depending on the application.

The unsaturated polyester thus obtained is
An unsaturated polyester resin can be obtained by dissolving it in a monomer copolymerizable with it, for example, styrene, vinyltoluene, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, diallyl phthalate, diallyl terephthalate. The compounding amount of the monomer to be copolymerized is preferably at most about 50% by weight.

The unsaturated polyester resin used for waste PET according to the present invention can be used in combination with organic or inorganic reinforcing materials, fillers, pigments, mold release agents, thermoplastic polymers and the like. .

[0021]

EXAMPLES Examples will be shown below in order to facilitate understanding of the present invention.

Example 1 In a 1-liter separable flask equipped with a stirrer, a fractionating condenser, a dropping funnel, and a gas inlet tube with a thermometer, waste PET coarsely crushed into rice grains (transparent product: about 90%, green) 230 g of colored type (about 10%) was charged, and the internal temperature was 26
After heating to 5 to 270 ° C. (about 1 hour), 80 g of purified 1,2-butanediol was added dropwise over 30 minutes while stirring. The boiling point of 1,2-butanediol is 190.
Despite being at 5 ° C, no significant reflux of 1,2-butanediol was observed. After the addition of 1,2-butanediol was completed, the temperature was kept at 235 to 240 ° C. and stirring was continued for 2 hours. It was confirmed that the contents became uniform, so the temperature was lowered to 200 ° C. and nitrogen gas was added. Under an air stream, 78 g of maleic anhydride was further added to proceed with esterification. The resulting unsaturated polyester has a final acid value of 32.8, PE
The T content was about 60% by weight. Next, 0.05 g of hydroquinone was added to this unsaturated polyester, and further 1
250 g of styrene was added and dissolved at 30 ° C. Obtained P
The ET-containing unsaturated polyester resin (A) was yellowish green and slightly clouded, and the viscosity was 6.1 poise.

PET-containing unsaturated polyester resin (A)
100 parts by weight, 1 part by weight of methyl ethyl ketone peroxide, 0.4 parts by weight of cobalt naphthenate (6% Co),
The composition to which 0.1 part by weight of dimethylaniline was added was cast into a mold in which two glass plates coated with a release agent were combined using a mold, and gelled at 25 ° C. in 35 minutes. The physical properties of the cast product obtained by gelling and post-curing at 80 ° C. for 2 hours were well balanced as shown in Table 1. The physical property values were measured according to JIS K-6911.

[0024]

[Table 1] Tensile strength (kg / mm ² ) 5.5 Tensile modulus (kg / mm ² ) 330 Elongation rate (%) 2.0 Bending strength (kg / mm ² ) 10.9 Bending elastic modulus ( kg / mm ² ) 370 Heat distortion temperature (℃) 101

Comparative Example 1 In the same separable flask used in Example 1, 230 g of waste PET roughly crushed to a grain size of rice and 80 g of purified 1,2-butanediol were simultaneously charged and heated. In the dropping method of 1,2-butanediol as in Example 1, it takes about 2 hours in about 1 hour.
It was possible to add 1,2-butanediol dropwise at 65 to 270 ° C, but when waste PET and 1,2-butanediol were simultaneously charged, 1,2-butanediol boils at a temperature of about 210 ° C. It took about 3.5 hours until the mixture was refluxed and could be stirred in a porridge state, and a uniform resin liquid could not be obtained. The reason for this seems to be the decomposition of 1,2-butanediol, but the esterification after addition of maleic anhydride did not result in an acid value of 100 or less, and a uniform resin liquid could not be obtained until the end. .

Example 2 In a separable flask similar to that used in Example 1, waste PET (about 90% of transparent product, about 10% of green colored type) 27 was used.
After charging 0 g and melting at 265 to 270 ° C., 1,
60 g of 2-butanediol was added dropwise over 60 minutes.
After the addition of 1,2-butanediol was completed, the mixture was stirred at a temperature of 240 ° C. for 2 hours to obtain a uniform resin liquid. Next, temperature 200 ℃
Then, 79 g of fumaric acid was added and esterification was carried out under a nitrogen gas stream to give a final acid value of 40.1. PET content is about 6
It was 9%. Hydroquinone (0.05 g) was added to the obtained unsaturated polyester and dissolved in 395 g of styrene. The resulting unsaturated polyester resin (B) containing PET was yellowish green and slightly clouded and had a viscosity of 4.9 poise. The styrene content was about 50% by weight, but no styrene separation was observed.

A composition in which 100 parts by weight of the PET-containing unsaturated polyester resin (B) is mixed with 1 part by weight of methyl ethyl ketone peroxide, 0.4 parts by weight of cobalt naphthenate (6% Co), and 0.1 parts by weight of dimethylaniline. The physical properties of the cast product obtained by curing the product in the same manner as in Example 1 are shown in Table 2.
It seemed to be seen in.

[0028]

[Table 2] Tensile strength (kg / mm ² ) 5.3 Tensile modulus (kg / mm ² ) 350 Elongation rate (%) 2.1 Bending strength (kg / mm ² ) 9.5 Bending elastic modulus ( kg / mm ² ) 370 Heat distortion temperature (℃) 87

Example 3 In a 1 liter separable flask equipped with a stirrer, a fractionating condenser, a dropping funnel, and a gas inlet tube with a thermometer, waste PET crushed into rice grains (about 90% of transparent product, green color) 230 g of colored type (about 10%) was charged, and the internal temperature was 26
After heating to 5 to 270 ° C (about 1 hour), 90 g of neopentyl glycol is added with a dropping funnel equipped with a heating device.
Was heated to 130 ° C. and melt-dropped over 30 minutes. No reflux of neopentyl glycol was observed. After completion of dropping neopentyl glycol, the temperature is adjusted to 235 to 240 ° C.
It was kept for 2 hours and stirred. It was observed that the contents were uniform. The temperature was lowered to 200 ° C., and 78 g of maleic anhydride was further added in a nitrogen gas stream to promote esterification.
The resulting unsaturated polyester has a final acid value of 34.9,
The PET content was about 58%. Next, add 0.05 g of hydroquinone, and add styrene 270 at 130 ° C.
g was added and dissolved. The obtained PET-containing unsaturated polyester resin (C) was yellowish green, slightly clouded, and had a viscosity of 5.4 poise.

Unsaturated PET resin containing PET (C)
100 parts by weight, methyl ethyl ketone peroxide 1 part by weight, cobalt naphthenate (6% Co) 0.5 part by weight,
When the composition containing 0.1 part by weight of dimethylaniline was cast in the same mold as in Example 1, gelation occurred at 25 ° C. in 18 minutes. After gelation, the physical properties of the cast product obtained by post-curing at 80 ° C. for 2 hours were well balanced as shown in Table 3.

[0031]

[Table 3] Tensile strength (kg / mm ² ) 6.1 Tensile elastic modulus (kg / mm ² ) 330 Elongation rate (%) 2.2 Bending strength (kg / mm ² ) 11.0 Bending elastic modulus ( kg / mm ² ) 380 Heat distortion temperature (℃) 98

Comparative Example 2 In the same separable flask used in Example 3, 230 g of waste PET (about 90% of transparent product, about 10% of green colored type) coarsely crushed into rice grains and 90 g of neopentyl glycol were placed. Were simultaneously charged and heated. In the dropping method of neopentyl glycol of Example 3, 265 to 27 are obtained in about 1 hour.
It became 0 ° C and dripping became possible, but when waste PET and neopentyl glycol were simultaneously charged, the temperature was about 220 ° C.
As a result, boiling of neopentyl glycol, condensation and attachment to the condenser occurred, and a uniform system could not be obtained.

Example 4 In a separable flask similar to that used in Example 1, waste PET (about 90% of transparent product, about 10% of green colored type) was used.
After charging 0 g and heating and melting at 260 to 265 ° C.,
107 g of dipropylene glycol was added dropwise over 60 minutes. After adding dipropylene glycol, the temperature is 240.
The mixture was stirred at 0 ° C for 2 hours to obtain a uniform resin liquid. Then temperature 20
70 g of fumaric acid was added at 0 ° C., and esterification was performed under a nitrogen gas stream to give a final acid value of 34.7. The PET content was about 62%. Hydroquinone (0.07 g) was added to the obtained unsaturated polyester and dissolved in 360 g of styrene. The obtained PET-containing unsaturated polyester resin (D) was yellow-green and slightly turbid, and had a viscosity of 6.
It was 1 poise. Further, in the PET-containing unsaturated polyester resin (D), separation of styrene was not recognized.

Composition containing 100 parts by weight of the PET-containing unsaturated polyester resin (D), 1 part by weight of methyl ethyl ketone peroxide, 0.5 part by weight of cobalt naphthenate (6% Co), and 0.1 part by weight of dimethylaniline. The physical properties of the cast product obtained by curing the product in the same manner as in Example 3 are shown in Table 4.
It seemed to be seen in.

[0035]

[Table 4] Tensile strength (kg / mm ² ) 7.4 Tensile modulus (kg / mm ² ) 300 Elongation rate (%) 3.8 Bending strength (kg / mm ² ) 12.9 Bending elastic modulus ( kg / mm ² ) 310 Heat distortion temperature (℃) 79

Example 5 In a separable flask similar to that used in Example 3, a floppy disk (PET: about 97) was used as waste PET and was roughly crushed into rice grains.
%, Magnetic powder about 3%), charged 280 g, 265-270
After melting at ℃, 2-methylpropanediol-1,3
72 g was added dropwise over 30 minutes. After forming a uniform solution, glycol decomposition was further performed at 230 to 235 ° C. for 2 hours. Then the temperature is lowered to 200 ° C. and maleic anhydride 5
4 g was melt-dropped. After continuing the esterification at 205 ° C in a nitrogen gas stream to adjust the acid value to 59.4 and then reacting for 1.5 hours under a reduced pressure of about 20 Torr, the acid value was 29.1. 0.16 g of hydroquinone was added and further dissolved in 400 g of styrene at a temperature of 130 ° C. An unsaturated polyester resin (E) having a dark brown color and a viscosity of 11.4 poise was obtained.

100 parts by weight of unsaturated polyester resin (E), 5 parts by weight of styrene, 0.1 part by weight of paraffin having a melting point of 50 to 52 ° C., 10 ppm of silicon defoamer, 0.5 part by weight of cobalt naphthenate, dimethylaniline. A composition prepared by adding 0.2 part by weight of the solution to a uniform solution and adding 1 part by weight of methyl ethyl ketone peroxide to the composition gradually gelled after 35 minutes and reached a maximum exothermic temperature of 128 ° C. A coating film obtained by coating the above composition on a Bondellite steel plate to a thickness of 100 μm gelled in about 40 minutes and became tack-free after 2 hours. The pencil hardness of the coating film after standing overnight is 2H ~
Adhesion was confirmed to be sufficient in a 3H, cross-cut test. Further, in the salt spray test, even after 350 hours, peeling of the coating film and spread of rust were not observed at all.

[0038]

EFFECTS OF THE INVENTION Since the present invention is configured as described above, even if the ratio of glycol used is relatively small relative to the ratio of waste PET used, the waste PET can be smoothly decomposed into glycol, and the PET content can be improved. An unsaturated polyester and an unsaturated polyester resin having a high rate can be obtained, and the excellent physical properties of the unsaturated polyester and the unsaturated polyester resin can be utilized for a wide range of applications.

Claims (5)

[Claims] 1. The recovered polyethylene terephthalate is melted in an amount of 20 to 90 mol% (repeating unit is 1 mol), and the melted polyethylene terephthalate is added to the melt.
After 80 to 10 mol% of glycol is sequentially added to decompose the glycol until it becomes homogeneous, a necessary amount of α, β-unsaturated polybasic acid or its acid anhydride is added, and esterification is further performed to a necessary stage. A method for producing an unsaturated polyester characterized by the following. 2. The method for producing an unsaturated polyester according to claim 1, wherein the glycol is 1,2-butanediol. 3. The method for producing an unsaturated polyester according to claim 1, wherein the glycol is a glycol having a methyl group. 4. The glycol having a methyl group is neopentyl glycol, dipropylene glycol or 2-
The method for producing an unsaturated polyester according to claim 3, which is methylpropanediol-1,3. 5. A method for producing an unsaturated polyester resin, which comprises blending the unsaturated polyester obtained by the method according to claim 1 with a monomer copolymerizable with the unsaturated polyester.