KR20200068036A - Method for reprocessing recycled phenol formaldehyde resin powders - Google Patents

Abstract

A method of reprocessing recycled phenol formaldehyde resin powders comprises the steps of: a) dispersing the recycled phenol formaldehyde resin powders and phenol formaldehyde prepolymers in a dispersion medium to form a matrix dispersion; and b) inducing a condensation reaction of the matrix dispersion to form a resin-based product.

Description

Method for reprocessing recycled phenol formaldehyde resin powders}

The present disclosure relates to a method for reprocessing phenol formaldehyde resin powder, and more particularly, to a method for reprocessing recycled phenol formaldehyde resin powder.

Commonly used Bakelite resin products are usually manufactured by impregnating a phenol formaldehyde resin with a reinforcing material such as paper, fabric, glass, etc., to form a blank, and then hot pressing the blank. It is a phenol formaldehyde resin product. Bakelite resin products are widely used as insulating parts in various electrical devices and/or transportation vehicles because of their excellent electrical, mechanical, and processing properties such as insulation, abrasion resistance, heat resistance, and flame retardancy.

However, the process of treating and recycling bakelite resin products can have a negative impact on the environment, for example carbon dioxide emissions.

Accordingly, it is an object of the present disclosure to provide a method of reprocessing a recycled phenol formaldehyde resin powder, such as recycled bakelite resin powder, to overcome the drawbacks of the prior art described above.

According to the present disclosure, a method for reprocessing recycled phenol formaldehyde resin powders is provided, which includes the following steps:

a) dispersing the regenerated phenol formaldehyde resin powder and the phenol formaldehyde prepolymer in a dispersing medium to form a matrix dispersion; And

b) condensation reaction of the matrix dispersion to form a resin-based product.

The recycled phenol formaldehyde resin powder can be effectively reused to produce new resin based products with improved properties by the method of reprocessing the recycled phenol formaldehyde resin powder according to the present disclosure.

One embodiment of the method for reprocessing a recycled phenol formaldehyde resin powder according to the present disclosure includes the following steps:

Iii) forming a phenol formaldehyde prepolymer by adding formaldehyde and phenol in the presence of a base catalyst by addition reaction and condensation reaction;

Ii) dispersing the regenerated phenol formaldehyde resin powder and the phenol formaldehyde prepolymer in a dispersing medium to form a matrix dispersion;

Iii) impregnating the matrix dispersion with a reinforcing material to obtain a resin-based product precursor; And

Iv) condensing the matrix dispersion by hot pressing the resin-based product precursor to form a resin-based product.

The phenol formaldehyde prepolymer formed in step iii) has hydroxymethyl groups, each of which is ortho and/or para in the phenolic moiety of the regenerated phenol formaldehyde resin powder. Can react with hydrogen. Thus, a new resin based product can be formed by condensation reaction of a phenol formaldehyde prepolymer and a regenerated phenol formaldehyde resin powder in a matrix dispersion, in particular, a matrix dispersion.

Examples of useful base catalysts in step iii) are sodium hydroxide, potassium hydroxide, barium hydroxide, ethylene diamine, triethylene diamine, dimethyl ethanol amine ( dimethylethanolamine) and combinations thereof. The base catalyst used in the following examples is sodium hydroxide in the form of an aqueous solution.

In certain embodiments, the recycled phenol formaldehyde resin powder has a particle size of 50 μm or less.

In certain embodiments, the molar ratio of formaldehyde to phenol used in step VII ranges from 0.7:1 to 2.5:1.

In certain embodiments, the recycled phenol formaldehyde resin powder used in step ii is in an amount ranging from 5 phr (based on 100 parts by weight of phenol formaldehyde prepolymer) to 100 phr.

The dispersion medium is used to adjust the solid content and viscosity of the matrix dispersion. In certain embodiments, the dispersion medium is an organic solvent. A non-limiting example of an organic solvent is methanol.

In certain embodiments, a modifier is added to the matrix dispersion prior to the step VII. Examples of modifiers include, but are not limited to, alkoxy-substituted silanes, boric acid derivates, and combinations thereof.

In certain embodiments, the alkoxy substituted silane is, but is not limited to, methyl trimethoxysilane. When an alkoxy substituted silane is used as a modifier, it is in an amount ranging from 1 phr to 30 phr.

In certain embodiments, examples of boric acid derivatives include boric acid (B(OH) ₃ ), boronic acid (RB(OH) ₂ , where R is a substituent), borinic acid (RR'- B(OH), where R and R'are each a substituent), and combinations thereof. When a boric acid derivative is used as a modifier, it is in an amount ranging from 1 phr to 20 phr. In the following examples, boric acid is used as a modifier.

In certain embodiments, the reinforcement is a paper sheet, a fabric web, or the like, or a combination thereof. The reinforcing material used in the following examples is a sheet of paper from a roll of paper.

In certain embodiments, the hot press in step ⅳ is performed at a temperature of about 150 °C to about 180 °C.

Hereinafter, embodiments of the present disclosure will be described. It will be understood that these examples are illustrative and explanatory and should not be construed as limitations on the present disclosure.

Example 1:

Paraformaldehyde (53 g) was dissolved in water (60 g) and then mixed with phenol (94 g) to form a uniform mixture. By adding aqueous sodium hydroxide solution (3 g; 40% by weight) at 100° C. under reflux for about 2 hours under reflux, the pH of the mixture was adjusted to a value of 8.5 to 9.0 to promote addition and condensation reactions. (catalyze) A phenol formaldehyde prepolymer was formed.

To the phenol formaldehyde prepolymer, bakelite resin powder (5 phr; particle size: 50 μm (about 300 mesh); obtained by pulverizing and polishing the recycled bakelite resin product), followed by methanol (90 g) to add solid content Was adjusted to 50% and a viscosity adjusted matrix dispersion was obtained.

The sheet of paper continuously fed from the roll paper was impregnated with the matrix dispersion, followed by evacuation and concentration to remove water and phenol. Subsequently, the paper sheet impregnated with the matrix dispersion was passed through an oven at 120° C. at a rate of 30 m/min to undergo a condensation reaction, and then dried and cut to obtain a semi-solidified resin-based sheet.

Five semi-solidified resin sheets were sandwiched between two smooth stainless steel sheets, and subjected to additional condensation reaction by hot pressing at a pressure of 700 mmHg and a temperature of 150°C to 180°C for 30 minutes to achieve a thickness of about 0.5 to 0.7 mm. A new bakelite plate was obtained. It should be noted that the number of semi-solidified resin-based sheets for forming a new bakelite plate can be varied according to specific requirements.

Examples 2 to 5:

The procedure of Examples 2 to 5 was similar to that of Example 1 except that the bakelite resin powder was used in amounts of 10 phr, 20 phr, 30 phr and 50 phr, respectively.

Example 6:

The procedure of Example 6 was similar to that of Example 1, except that methyl trimethoxysilane (20 phr) was further added to the phenol formaldehyde prepolymer.

Example 7:

The procedure of Example 7 was similar to that of Example 1 except that boric acid (10 phr) was additionally added to the phenol formaldehyde prepolymer.

Example 8:

The procedure of Example 8 was similar to that of Example 1, except that methyl trimethoxysilane (20 phr) was additionally added to the phenol formaldehyde prepolymer and bakelite resin powder was used in an amount of 60 phr.

Example 9:

The procedure of Example 9 is Example 1, except that methyl trimethoxysilane (20 phr) and boric acid (10 phr) are additionally added to the phenol formaldehyde prepolymer, and the bakelite resin powder is used in an amount of 60 phr. The procedure was similar.

Comparative Example 1:

The procedure of Comparative Example 1 was similar to that of Example 1, except that the bakelite resin powder was not used.

Measure the properties of the new Bakelite plate:

For each of the new bakelite plates of Examples 1 to 9 and Comparative Example 1, Shore D hardness, flexural strength and softening temperature (T _max ) were measured. The results are shown in Table 1 below.

Shore D hardness Flexural strength (kg/cm ² ) T _max (°C) Example 1 91 18.5 378 Example 2 91 18.5 379 Example 3 92 18.4 380 Example 4 92 18.0 382 Example 5 92 17.8 385 Example 6 94 19.4 383 Example 7 94 19.4 385 Example 8 94 19.4 395 Example 9 94 19.4 400 Comparative Example 1 90 19.4 375

In view of the above, the method for reprocessing the recycled phenol formaldehyde resin powder according to the present disclosure can effectively overcome the drawbacks of the above-mentioned prior art by effectively reprocessing the recycled phenol formaldehyde resin powder such as recycled bakelite resin powder. In addition, as shown in Table 1, the new resin-based product thus obtained (i.e., a new bakelite plate) has improved hardness and thermal stability.

In the above detailed description, numerous specific details have been stated for purposes of explanation to provide a thorough understanding of the implementation(s). However, it will be apparent to one skilled in the art that one or more other embodiments may be practiced without some of these specific details. It should also be understood that reference to "one embodiment", "an embodiment", an embodiment having an ordinal number, and the like throughout this specification means that a particular feature, structure, or characteristic may be included in the practice of the present disclosure. will be. In the detailed description, various features are sometimes grouped together in one implementation, a drawing, or a description thereof to assist in simplifying the present disclosure and understanding various aspects of the invention, and where appropriate, from one implementation in the practice of the present disclosure. It will be further understood that one or more features or specific details may be practiced with one or more features or specific details from other implementations.

Although the present disclosure has been described in terms of(s) regarded as exemplary embodiment(s), the present disclosure is not limited to the disclosed embodiment(s), and various arrangements included within the spirit and scope of the broadest interpretation. It will be understood that it is intended to cover all such modifications and equivalent arrangements inclusively.

Claims (13)

a) dispersing recycled phenol formaldehyde resin powders and phenol formaldehyde prepolymer in a dispersing medium to form a matrix dispersion; And
b) A method for reprocessing a recycled phenol formaldehyde resin powder comprising condensation reaction of the matrix dispersion to form a resin-based product. The regeneration according to claim 1, further comprising the step of forming a phenol formaldehyde prepolymer by adding and reacting condensation of formaldehyde and phenol in the presence of a base catalyst before step a). Method for reprocessing phenol formaldehyde resin powder. The recycled phenol of claim 1 or 2, further comprising the step of impregnating the matrix dispersion with a reinforcing material prior to step b) to obtain a resin-based product precursor. Method for reprocessing formaldehyde resin powder. The method of claim 3, wherein the step b) is performed by hot pressing the resin-based product precursor. The method according to any one of claims 1, 2, and 4, wherein the regenerated phenol formaldehyde resin powder has a particle size of 50 µm or less. The method for reprocessing a recycled phenol formaldehyde resin powder according to claim 2 or 4, wherein the molar ratio of formaldehyde to phenol is in the range of 0.7:1 to 2.5:1. The method according to any one of claims 1, 2, and 4, wherein the regenerated phenol formaldehyde resin powder is in an amount of 5 phr to 100 phr. The method according to any one of claims 1, 2 and 4, further comprising adding a modifier to the matrix dispersion prior to step b). . 9. The method of claim 8, wherein the modifier is selected from the group consisting of alkoxy-substituted silane, boric acid derivate, and combinations thereof. 10. The method of claim 9, wherein the modifier is an alkoxy substituted silane. 11. The method according to claim 10, wherein the alkoxy substituted silane is in an amount ranging from 1 phr to 30 phr. 10. The method of claim 9, wherein the modifier is a boric acid derivative, a method for reprocessing a recycled phenol formaldehyde resin powder. The method according to claim 12, wherein the boric acid derivative is in an amount ranging from 1 phr to 20 phr.