Resin with high thermal stability, with low reaction temperature and reaction time, no need for crosslinking agent

Abstract

The invention is an energy-saving resin production method with low reaction temperature and reaction time, without the need for any cross-linking agent, with high thermal stability, for use in the production of composites with high heat resistance; The invention is characterized in that the resorcinol-formaldehyde resin is modified with phenylboronic acid as an aromatic ring boron source and its thermal stability is increased by adding boron element to the structure of the resin, resorcinol in crystalline form; phenylboronic acid as an aromatic boron source; formaldehyde in 37% aqueous solution and with a minimum methanol content of 10%; sodium hydroxide in 10% aqueous solution as catalyst.

Description

[0001] DESCRIPTION

[0002] RESIN WITH HIGH THERMAL STABILITY, WITH LOW REACTION TEMPERATURE AND REACTION TIME, NO NEED FOR CROSSLINKING AGENT

[0003] TECHNICAL FIELD

[0004] The invention relates to a thermoset resin developed for use in the production of high heat-resistant composites.

[0005] PRIOR ART

[0006] Composite materials play a vital role in modern engineering and manufacturing processes. Various thermoplastic and thermosetting polymer matrices are used to develop composites that are resistant to high temperature (>1000°C), especially when exposed to high temperatures. These polymers have certain advantages and disadvantages. The selection of suitable matrix materials for high temperature composites depends on the properties and performance criteria required by the application.

[0007] Thermoplastic matrix composites are widely preferred due to their properties such as easy processability and reshapeability. However, the disadvantage of these matrices is that they melt under high temperature conditions and form a fluid residue. This melt residue evaporates at high temperatures and moves away from the composite. This situation reduces the high temperature resistance of the composite and is an important factor limiting the use of thermoplastic matrix composites in high temperature applications.

[0008] On the other hand, thermoset polymers are polymers that do not melt at high temperatures and can form char residue. This feature makes thermoset matrix composites more durable under high temperature conditions. Among thermoset polymers, phenolic resins are frequently used in high temperature composites because they have higher thermal stability than other thermoset polymers. These resins have excellent non-flammability properties and high temperature resistance, as well as flame retardant and smoke reduction properties.

[0009] Phenolic resins are divided into three groups as novolac type phenol-formaldehyde, resol type phenol-formaldehyde and also resorcinol-formaldehyde resin. Phenol- formaldehyde resins contain high reaction temperature, high reaction time, high curing (crosslinking) time and curing temperature. Novolac-type phenol-formaldehyde resins also require a curing agent. Resorcinol-formaldehyde resin, compared to phenolformaldehyde resins, provides low reaction time, low reaction temperature and low reaction temperature and time for curing. It does not require any crosslinking agent and can be cured even at room temperature. However, their thermal stability is lower than phenol-formaldehyde resins.

[0010] Reviews in the known art include phenol-formaldehyde resins and benzoxazine resins as publications. There is no formaldehyde resin with low reaction temperature and reaction time, no need for any crosslinking agent and high thermal stability.

[0011] As a result, all the problems mentioned above have made it necessary to innovate in the related field.

[0012] AIM OF THE INVENTION

[0013] The present invention is presented with the aim of eliminating the above-mentioned problems and making a technical innovation in the related field.

[0014] The main purpose of the invention is to present a resin structure with high temperature resistance suitable for use in composites.

[0015] Another purpose of the invention is to present an energy saving resin structure with low synthesis conditions and curing conditions.

[0016] Another purpose of the invention is to provide a resin with increased thermal stability suitable for use in composite product production.

[0017] Another purpose of the invention is to enable the production of composites with high temperature and high thermal resistance, suitable for use in heat shields and thermal protection systems, with the resin obtained.

[0018] BRIEF DESCRIPTION OF THE INVENTION

[0019] In order to realize all the purposes mentioned above and to be revealed from the detailed explanation below, the present invention is a resin having a low reaction temperature and reaction time, not requiring any crosslinking agent and having high thermal stability. The invention is a resin production method with low reaction temperature and reaction time, no crosslinking agent required, high thermal stability, and energy saving to be used in the production of composites with high heat resistance; its feature is to increase the thermal stability of the resin by modifying the resorcinol-formaldehyde resin with phenylboronic acid as an aromatic ring boron source and adding boron element to the structure of the resin. a. resorcinol in crystalline form; b. phenylboronic acid as aromatic boron source; c. formaldehyde in 37% aqueous solution and with a minimum of 10% methanol content; d. sodium hydroxide in 10% aqueous solution as catalyst is characterized by being provided in line with the reaction.

[0020] In order to obtain the mentioned resin with the mentioned components, a. Ensure homogeneous mixing by adjusting the formaldehyde / resorcinol molar ratio to 2; b. Adding 3%, 6%, 9% and 12% phenylboronic acid to the mixture by weight based on the total mixture weight and providing a homogeneous mixture; c. Adding sodium hydroxide aqueous base solution so that the pH value of the mixture is between 7.10-7.30; d. Continuing the reaction at a reaction temperature of 52-55°C and a reaction time of min 10 min under controlled heating and cooling; e. Cooling to stop the reaction

[0021] The modified viscous resorcinol-formaldehyde resin is obtained by carrying out the reaction in accordance with the processes.

[0022] In another preferred embodiment of the invention, phenylboronic acid modified viscous resorcinol-formaldehyde resin is obtained by cooling to 30°C to stop the reaction.

[0023] In another preferred embodiment of the invention, the reaction time is continued for 15 minutes. In another preferred embodiment of the invention, minimum 99% purity resorcinol and phenylboronic acid are used.

[0024] The scope of protection of the invention is set out in the claims and is by no means limited to what is described in this brief and detailed description for illustrative purposes. It is obvious that a person skilled in the art may, without departing from the main theme of the invention, come up with similar constructions in the light of the foregoing.

[0025] BRIEF DESCRIPTION OF THE FIGURES

[0026] The drawing showing the structure of the invention is given in Figure 1 .

[0027] A graph showing the results of the Thermogravimetric analysis is given in Figure 2.

[0028] The drawings are not intended to limit the scope of protection defined in the claims and should not be referred to in isolation without reference to the technical description in the description of the present invention for the purpose of interpreting the scope defined in those claims. The drawings are intended to describe the invention with clarity.

[0029] DETAILED DESCRIPTION OF THE INVENTION

[0030] In this detailed description, the resin with low reaction temperature and reaction time, no crosslinking agent required, high thermal stability is explained only with examples that will not create any limiting effect for a better understanding of the subject.

[0031] The subject of the invention is related to the thermoset resin developed to be used in the production of composites with high heat resistance.

[0032] The invention is an energy-saving resin production method with low reaction temperature and reaction time, without the need for any cross-linking agent, with high thermal stability, for use in the production of composites with high heat resistance; its feature is to modify the resorcinol-formaldehyde resin with phenylboronic acid as an aromatic ring boron source and to increase its thermal stability by adding boron element to the structure of the resin.

[0033] • resorcinol in crystalline form

[0034] • phenylboronic acid as an aromatic boron source • formaldehyde with a minimum of 10% methanol content in the form of 37% aqueous solution, sodium hydroxide as a catalyst in the form of 10% aqueous solution is characterized by being provided in accordance with the reaction.

[0035] Within the scope of the invention, resorcinol and phenylboronic acid are preferably used with a minimum purity of 99%.

[0036] The processes of modifying the said resorcinol-formaldehyde resin with phenylboronic acid as an aromatic ring boron source and adding boron element to the structure of the resin;

[0037] 1. Providing a homogeneous mixture by adjusting the formaldehyde / resorcinol molar ratio as 2;

[0038] 2. Adding phenylboronic acid to the mixture at 3%, 6%, 9% and 12% by weight based on the total mixture weight and providing a homogeneous mixture;

[0039] 3. Addition of 10% sodium hydroxide aqueous base solution so that the pH of the mixture is in the range of 7.10-7.30;

[0040] 4. Continuation of the reaction under controlled heating and cooling at a reaction temperature of 52-55°C and a reaction time of 15 min;

[0041] 5. Obtaining phenylboronic acid modified viscous resorcinol-formaldehyde resin by cooling to 30°C to stop the reaction;

[0042] The viscous resins obtained within the scope of the invention have a curing temperature of 80°C and a curing time of 4 hours.

[0043] Polymerization of phenylboronic acid modified resorcinol-formaldehyde resin in the presence of base catalyst;

[0044] Mixtures of resorcinol, formaldehyde and phenylboronic acid were polymerized in the presence of sodium hydroxide as base catalyst.

[0045] Resorcinol is an aromatic compound and has hydroxyl groups in the 1 st and 3rd regions attached to the benzene ring. The 2nd, 4th and 6th regions in the aromatic ring are reactive regions for chemical reactions. The reaction of resorcinol with formaldehyde is highly reactive. For this reason, the reaction temperature was kept below 60°C. Due to the high reactivity, the catalyst concentration (sodium hydroxide) was limited to 10%.

[0046] As a result of the reaction of resorcinol with formaldehyde in the presence of base catalyst, methylol groups are formed on the resorcinol ring. After condensation of methylols, methylene and ether bridges are formed.

[0047] Phenylboronic acid, a source of boron with aromatic rings, contains boron attached to the aromatic ring and two hydroxyl groups attached to boron. New boronate bridges are formed as a result of the reaction of methylol groups on the 2, 4 and 6 regions of the resorcinol ring and hydroxyl groups on the 1 and 3 regions with hydroxyl groups in the phenylboronic acid structure.

[0048] The structure of the modified formaldehyde resin obtained within the scope of the invention is given in Figure 1 .

[0049] The boronate groups in the resorcinolformaldehyde polymer structure in the reaction stage and the curing (crosslinking) stage provide increased thermal stability.

[0050] Characterization of phenylboronic acid modified resorcinol-formaldehyde resin;

[0051] The thermal stabilities of the resins were characterized using a Hitachi / STA 7200 Thermogravimetric analysis (TGA) instrument The graph showing the mentioned results is given in Figure 2. The modified resin obtained within the scope of the invention was compared with the pure (unmodified) resorcinol-formaldehyde resin. It was determined that the thermal stability of the resorcinol-formaldehyde resin obtained within the scope of the invention was increased.

[0052] It was also observed that the pure resorcinol-formaldehyde resin formed 49.7% coal residue at 1000°C and under nitrogen atmosphere. The coal residues with the resin obtained within the scope of the invention are in the range of 51 .2%-54.9%.

[0053] The resin obtained within the scope of the invention is a boron-modified resorcinol- formaldehyde resin with energy saving and high thermal stability, which can be used as a matrix material in carbon fiber reinforced composites resistant to high temperatures and as a flame retardant in materials when blended with other thermoplastic / thermoset polymers. The adhesive sector is also among the areas of use of resins. Resorcinol-formaldehyde resins are used in the wood adhesive sector. The improved resorcinol-formaldehyde resin within the scope of this invention can be used as a heat-resistant adhesive.

[0054] The scope of protection of the invention is specified in the claims given in the appendix and cannot be strictly limited to what is explained in this detailed description for the purpose of example. It is obvious that a person skilled in the art can present similar structures in the light of the above explanations and the technical drawings without deviating from the main theme of the invention.

Claims

CLAIMS1. A resin production method for the production of high heat-resistant composites, having low reaction temperature and reaction time, not requiring any crosslinking agent, having high thermal stability, and being energy-saving, characterized by; a. resorcinol in crystalline form; b. phenylboronic acid as a source of aromatic boron; c. formaldehyde in a 37% aqueous solution with a minimum methanol content of 10%; d. sodium hydroxide in a 10% aqueous solution as a catalyst, to enhance the thermal stability of the resin by modifying the resorcinolformaldehyde resin with phenylboronic acid as an aromatic ring boron source and incorporating the boron element into the resin structure.

2. The method steps for obtaining mentioned resin with the components as claimed in claim 1 characterized by; a. Providing a homogeneous mixture by adjusting the formaldehyde / resorcinol molar ratio to 2; b. Adding phenylboronic acid to the mixture at a ratio of 3%, 6%, 9% and 12% by weight based on the total weight of the mixture and providing a homogeneous mixture; c. Addition of sodium hydroxide aqueous base solution so that the pH of the mixture is in the range of 7.10-7.30; d. Continuation of the reaction under controlled heating and cooling at a reaction temperature of 52-55°C and a reaction time of min 10 min; e. Cooling to stop the reaction.

3. The method according to claim 2, characterized in that a phenylboronic acid modified viscous resorcinol-formaldehyde resin is obtained by cooling to 30°C to stop the reaction mentioned in step “e.”.

4. The method according to claim 2 wherein the reaction time is maintained for 15 min in step “d.”.

5. The method according to any one of the preceding claims, comprising resorcinol and phenylboronic acid with a minimum purity of 99%.

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