KR100672758B1 - Water-soluble baking enamel paint - Google Patents

Abstract

A water-soluble baking enamel paint is provided to have good physical properties such as boiling water resistance, gloss, hardness, solvent resistance, chemical resistance, adhesion, etc. The water-soluble baking enamel paint comprises 35-60wt% of an acrylic resin having a hydroxyl value of 20-70mgKOH/g, an acid value of 40-65mgKOH/g, a non-volatile material content of 50-70wt%, and a glass transition temperature of 0-30‹C, 4-10wt% of a cross-linkable melamine resin, 15-35wt% of a coloring pigment, 2-5wt% of a primary amine, 3-5wt% of butyl cellosolve, 0.4-3wt% of an additive including a dispersant for water-based paints, an antifoaming agent for water-based paints, a cross-linkable catalyst, and a flow regulator, 2-4wt% of an auxiliary solvent, and 10-20wt% of a water-soluble solvent.

Description

Water-soluble Baking enamel paint

The present invention relates to a calcined enamel paint, and more particularly, to a water-soluble calcined enamel paint coated on industrial steel.

In general, oil-based calcined enamel paints have excellent properties such as adhesion, hardness, high appearance, gloss, and the like, and are used as coating materials for steel materials such as cases of industrial machines and home appliances.

However, since the oil-based calcined enamel paint uses an organic solvent as a solvent, it has a harmful effect on environmental pollution and worker's health. In addition, since the discharge of organic solvents is regulated in the world as well as in Korea, the use of oil-based calcined enamel paints is currently being reduced.

In the case of automotive paints, the application of water-based paints has been considered since the late 80s and is currently being applied to the line, but the research and application of industrial paints is extremely limited. This is because water-soluble baking paint is highly affected by temperature and humidity, so it is very important to control the temperature and humidity of the coating line. However, since general industrial coating lines except for automotive coating lines are rarely controlled for temperature and humidity, defects such as flow, condensation, and boiling may occur when the water-soluble paint is used in the coating lines where humidity is not controlled at all. The problem is caused. Problems such as condensation and boiling are mainly caused due to the flow phenomenon.

An object of the present invention for solving the above problems is a water-soluble baking enamel capable of forming a three-dimensional network coating film when cured with an acrylic resin having a suitable range of hydroxyl group, acid value, glass transition temperature, and nonvolatile content as a main resin. The purpose is to provide paint.

  Water-soluble calcined enamel paint of the present invention for achieving the above object is an acrylic resin having a characteristic of 20 to 70, acid value of 40 to 65, nonvolatile content of 50 to 70% by weight, glass transition temperature of 0 to 30 ℃ 35-60 5% by weight, 5 to 35% by weight of colored melamine resin, 5 to 35% by weight of colored pigment, 2 to 5% by weight of primary amine, 10 to 20% by weight of water-soluble solvent, 3 to 5% by weight of butyl cellosolve %, 2 to 4% by weight of an auxiliary solvent, and 0.4 to 3% by weight of an additive including a dispersant for an aqueous paint, an antifoaming agent for an aqueous paint, a catalyst for crosslinking, and a flow control agent.

In the water-soluble baking enamel paint, the melamine resin for crosslinking is preferably hexamethoxy melamine resin or modified hexamethoxy melamine resin. In particular, the use ratio of the melamine resin for crosslinking and the acryl resin in the water-soluble calcined enamel paint satisfies 1: 5 to 7.

The crosslinking catalyst is a blocked acid catalyst having a minimum curing temperature of 80 to 100 ° C., and the flow control agents include organoclay, bentonite, montmorillonite, inorganic clay smectite and the like. The water-soluble solvent is ion-exchanged water, and the auxiliary solvent is a synthetic isoparaffinic solvent having a minimum flash point of 56 ° C or higher and a boiling point of 180 ° C or higher.

The water-soluble calcined enamel paint prepared with the above composition improves the organic solvent emission problem, which is a problem of the conventional oil-based calcined enamel paint, and is excellent in boiling water, gloss, hardness, etc. even when coated in a work space where humidity cannot be controlled. Can be formed.

Hereinafter, the water-soluble baking enamel paint according to the present invention will be described in detail.

Water Soluble Baking Enamel Paint

The water-soluble calcined enamel paint of the present invention is a paint that can be applied to steel materials in a work space where humidity control is not applied, and has a hydroxyl group and an acid value, a glass transition temperature, and a nonvolatile content in an appropriate range. Acrylic resins, crosslinking melamine resins, colored pigments, primary amines, water-soluble solvents, butyl cellosolves, auxiliary solvents, dispersants for water-based paints, defoamers for water-based paints, crosslinking catalysts and flowability It has a composition containing an additive containing a control agent.

Specifically, the acrylic resin is a water-soluble acrylic resin in which a hydroxyl group (-OH) and a carboxyl group (-COOH), which are reactors, are introduced into a polymer chain, and a hydroxyl value of 20 to 70 mgKOH / g, an acid value of 40 to 65 mgKOH / g, and a nonvolatile content of 50 to 70 weight. %, Glass transition temperature of 0 to 30 ℃.

An acrylic resin having the above properties is prepared by synthesizing the following components. 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate is applied as a first component for imparting a hydroxyl group of the acrylic resin, and as a second component for imparting a carboxyl group to the acrylic resin, Acrylic acid or methacrylic acid is applied. In addition, examples of the acrylic monomer which is a component that is applied to the production of the resin is methyl methacrylate, methyl acrylate, ethyl acrylate, styrene, 2-ethylhexyl acrylate, normal-butyl acrylate, 2-hydroxy Ethyl acrylate, 2-hydroxyethyl methacrylate, acrylic acid, methacrylic acid, fumaric acid, maleic acid, etc. are mentioned.

When the hydroxyl value is less than 20 mgKOH / g in the acrylic resin prepared from these components, the reactivity of the crosslinking melamine resin, which is a crosslinking resin, and the acrylic resin is reduced, resulting in a decrease in adhesion and hardness. On the other hand, when the hydroxyl value exceeds 70mgKOH / g, the hardness of the formed coating film is excellent, but the problem of poor impact is caused. Therefore, the hydroxyl value of the said acrylic resin is 20-70 mgKOH / g, Preferably it is 25-65 mgKOH / g.

In addition, when the acid value of the acrylic resin is 40 mgKOH / g or less, there is a problem in the acceptance of the paint formed. On the other hand, when the acid value exceeds 65mgKOH / g, the water resistance and boiling water resistance of the coating film formed of the paint is weak. Accordingly, the acid value of the acryl resin is 40 to 65 mgKOH / g, preferably 45 to 60 mgKOH / g.

In addition, when the volatile content of the acrylic resin is less than 50% by weight, it is difficult to form a coating film having an appropriate thickness during the painting process because the content of solids for forming the coating film is relatively small. On the other hand, when the nonvolatile content exceeds 70% by weight, the viscosity of the acrylic resin to be formed is high, which causes a problem of obtaining a desired paint. Therefore, the non-volatile content of the acryl resin is 50 to 70% by weight, preferably 55 to 65% by weight.

In addition, the hardness of the coating film formed when the glass transition temperature of the acrylic resin is less than 0 ℃ can not reach the required level, the hardness of the coating film formed when it exceeds 30 ℃ is excellent, but the coating film cracking, adhesion, etc. Defects are caused. Therefore, the glass transition temperature of the said acrylic resin is 0-30 degreeC, Preferably it is 5-25 degreeC.

It is applied to prepare a water-soluble baking enamel paint of the present invention, the water-soluble baking enamel paint formed when the content of the acryl resin having the above characteristics is less than 35% by weight, it is difficult to form a coating film that satisfies the required properties such as gloss, adhesion . If the content exceeds 60% by weight, it is difficult to form a coating film that satisfies the required properties such as hardness and cover-up. Therefore, 35 to 60 wt% of the acrylic resin is included in the water-soluble baking enamel paint, and preferably 40 to 55 wt%.

The water-soluble baking enamel paint contains a melamine resin for crosslinking. Examples of the crosslinking melamine resins include hexamethoxymelamine resins and modified hexamethoxymelamine resins. In particular, examples of the hexamethoxymelamine resin may be Cymel 300, 301, 303, 325, 327, manufactured by Cytec (USA), and the like.

When the content of the cross-linking melamine resin is less than 4% by weight, a phenomenon occurs that the hardness of the coating film formed of the paint becomes weak. On the other hand, when it exceeds 10% by weight, the hardness of the formed coating film is increased, but the coating film is fragile and the problem that the adhesion is weak. Therefore, the water-soluble baking enamel paint contains about 4 to 10% by weight of the melamine resin for crosslinking.

Specifically, the amount of the crosslinking melamine resin used to form the coating material preferably satisfies the use ratio of about 1: 5 to 7 for the crosslinking melamine resin and the acryl resin. That is, 7/1, 6/1, or 5/1 (acrylic resin / melamine resin) of the amount of acrylic resin used is used. In this case, the amount used is for the solid content of the acrylic resin and melamine resin. When the use ratio of the acrylic resin and the melamine resin for crosslinking is 5/1 or less, the hardness of the formed coating film is increased, but the coating film is fragile and the adhesion is weak. On the other hand, when the application ratio is 7/1 or more, the hardness of the formed coating film becomes weak. Therefore, it is preferable that the use ratio of the said acrylic resin and the melamine resin for hardening satisfy | fills the range of 5/1-7/1.

As said coloring pigment, an organic pigment, an inorganic pigment, metallic pearl pigment, etc. can be used as a substance which gives a color to the said coating material.

When the content of the colored pigment is less than 5% by weight, a problem occurs in hiding power of the coating. On the other hand, when the content exceeds 35% by weight, the pigment ratio is too high, the hardness of the coating film is raised, but the coating film is broken. Therefore, about 5 to 35 weight% of said coloring pigment is contained in the said water-soluble baking enamel paint, Preferably it is contained 10 to 35 weight%.

The primary amine is applied to neutralize the acryl resin. Examples of the primary amine include dimethylamine, 2-amino-methylpropanol, 2-dimethyl amino-2-propanol, N, N-dimethylethanolamine, triethylamine, N-methyl-diethanolamine, morpholine, di Ethanolamine, ammonia water and the like.

When the content of the primary amine is less than 2% by weight, there is a problem in that the coating is not water-soluble. On the other hand, when the content is more than 5% by weight, the coating film formed is a problem that the dryness, water resistance is weak. Thus, about 2 to 5% by weight of the primary amine is included in the water-soluble baking enamel paint.

For example, it is preferable to calculate the amount of the primary amine used based on the following equation.

---[수학식]

--- [mathematical formula]

(In the above formula, S is the solid content of the resin, M is the molecular weight of the amine, A is the acid value of the resin, D: the degree of neutralization.)

If the content of the butyl cellosolve is less than 3% by weight, a problem is caused in pigment dispersion during paint production, and if the content is more than 5% by weight, the drying property becomes weak and the flowability becomes poor after coating. Therefore, the water-soluble baking enamel paint contains about 3 to 5 wt% of the butyl cellosolve.

The additive includes a dispersant for an aqueous paint, an antifoaming agent for an aqueous paint, a catalyst for crosslinking and a flow control agent, and includes about 0.4 to 3 wt% in the water-soluble baking enamel paint.

Specifically, the dispersant for water-based paints included in the additive is used in consideration of the wettability and dispersibility of the pigment. Examples of the dispersant for water-based paints include BYK-181, BYK183, BYK-184, BYK-190, BYK-192, and the like, manufactured by BYK (Germany).

If the amount of the water-based paint dispersant is less than 0.1% by weight, a phenomenon such as re-agglomeration and sedimentation of the pigment occurs, resulting in a poor appearance of the coating film formed, and a coating film formed when the amount of the dispersant is more than 0.5% by weight. Water resistance, hardness and the like become weak. Therefore, 0.1 to 0.5% by weight of the dispersant for water-based paint is used, preferably 0.1 to 0.4% by weight.

The antifoaming agent for water-based paints contained in the additive is used to remove bubbles generated during paint production and bubbles generated during coating. Examples of the above-mentioned antifoaming agent for water-based paints include BYK-011, BYK-019, BYK-020, and the like made by modified polysiloxane type BYK (Germany).

If the amount of the anti-foaming agent for water-based paint is less than 0.1% by weight, it is difficult to expect the antifoaming effect, whereas if it exceeds 0.5% by weight, creating occurs in the coating film formed. Therefore, 0.1 to 0.5% by weight of the antifoaming agent for water-based coating is used, preferably 0.1 to 0.4% by weight.

The crosslinking catalyst included in the additive may lower the curing temperature of the paint and control the flowability since curing starts at a low temperature. As an example of the said crosslinking catalyst, a crosslinking catalyst is mentioned for the blocked acid applicable to water-soluble paint. In particular, the blocked acid crosslinking catalyst preferably uses a product having a minimum curing temperature between 80 and 100 ° C.

When the amount of the crosslinking catalyst is less than 0.1% by weight, it is difficult to expect the effect of using the catalyst, whereas when the amount of the crosslinking catalyst is more than 0.5% by weight, the hardness of the formed coating becomes too strong so that the coating film is broken or the adhesion is weak. . Therefore, 0.1 to 0.5% by weight of the soluble catalyst is used, preferably 0.1 to 0.4% by weight.

The flow control agent included in the additive plays a role in improving the flow of the coating film formed during the coating of the paint and the freshness of the coating film. Examples of the flow control agent include organocrane bentonite, montmorillonite and inorganic crain smectite. When the amount of the flow control agent is 0.3 wt% or less, the flow preventing effect cannot be expected, whereas when the flow control agent exceeds 0.1 wt%, the paint viscosity to be formed becomes too high. Therefore, 0.3 to 0.1% by weight of the flow control agent is used.

 The co-solvent is applied to improve the appearance (smoothness) and the boiling property of the coating film to be formed. As an example of the said cosolvent, a synthetic isoparaffin solvent is mentioned. It is preferable to use the synthetic isoparaffin solvent having a high flash point of 56 ° C or higher and a boiling point of 180 ° C or higher.

When the content of the auxiliary solvent included in the water-soluble baking enamel paint is less than 2% by weight, the above-described effects cannot be expected. On the other hand, when the content is more than 4% by weight, the coating film formed on the coating film is poor in appearance. Is generated. Thus, the auxiliary solvent is included in the water-soluble baking enamel paint about 2 to 4% by weight.

The water-soluble solvent uses ion-exchanged water as a main solvent for forming the paint. If the content of the water-soluble solvent contained in the water-soluble baking enamel paint is less than 10% by weight, the viscosity of the formed paint is increased, and if the content is more than 20% by weight, the viscosity of the cut formed is significantly low. Losing problems are caused. Therefore, the water-soluble solvent is contained in about 10 to 20% by weight, preferably about 12 to 20% by weight in the water-soluble baking enamel paint.

Hereinafter, the present invention will be described through the following synthesis examples, examples and evaluation examples. However, the technical scope of the present invention is not limited by these.

Synthesis Example 1

In a 2 L four-necked flask equipped with a stirrer, a heater, a thermometer, and a condenser, 27 parts by weight of ethylene glycol monobutyl ether and 0.5 part by weight of maleic acid were added, and the temperature was raised to 127 ° C.

23 parts by weight of methyl methacrylate, 12 parts by weight of normal-butyl acrylate, 8.5 parts by weight of 2-ethylhexyl acrylate, 15 parts by weight of styrene, 7 parts by weight of 2-hydroxyethyl acrylate, 4.5 parts by weight of acrylic acid 0.2 parts by weight of benzoyl peroxide (75% hydrate) was added and stirred uniformly until the peroxide initiator was completely dissolved to form a monomer mixture. Subsequently, the monomer mixture was added to a dropping funnel and added dropwise to the four neck flask at the same temperature for 3 hours. After completion of the dropping, the mixture was maintained at 130 ° C. for 1 hour, and 1 part by weight of ethylene glycol monobutyl ether and 0.1 part by weight of benzoyl peroxide (75% hydrate) were mixed and added to the flask to further react the unreacted monomer. Subsequently, after holding for 1 hour, 1 part by weight of ethylene glycol monobutyl ether and 0.1 part by weight of benzoyl peroxide (75% hydrate) were added followed by further reaction of the unreacted monomer. And again after maintaining for 1 hour and finally by adding 1 part by weight of ethylene glycol monobutyl ether and 0.1 parts by weight of benzoyl peroxide (75% hydrate) to react the unreacted monomer. Thereafter, the reaction was completed by cooling to 30 ° C. to obtain a transparent acrylic resin having a solid content of 70% by weight, a Gardner viscosity Z4 to Z7, an acid value of 53 mgKOH / g, a hydroxyl value of 48 mgKOH / g, and a glass transition temperature of 19 ° C.

Synthesis Example 2

In a 2 L four-necked flask equipped with a stirrer, a heater, a thermometer, and a condenser, 27 parts by weight of an aromatic solvent such as xylene and toluene were used alone or as a mixed solution, and the temperature was raised to 130 ° C.

15 parts by weight of styrene, 14.5 parts by weight of methyl methacrylate, 20 parts by weight of isobutyl methacrylate, 10 parts of 2-ethylhexyl acrylate, 9 parts by weight of 2-hydroxyethyl acrylate, 1.5 parts by weight of methacrylic acid 0.7 parts by weight of benzoyl peroxide (75% hydrate) was added and stirred uniformly until the peroxide initiator was completely dissolved to form a monomer mixture.

The monomer mixture was added to the dropping funnel and added dropwise to the four neck flask at the same temperature for 3 hours. After completion of the dropping, the mixture was maintained at 130 ° C. for 1 hour, and 1 part by weight of xylene and 0.1 part by weight of benzoyl peroxide were uniformly mixed, followed by further addition in the flask to further react the unreacted monomer. After further maintaining for 1 hour, 1 part by weight of xylene and 0.1 part by weight of benzoyl peroxide were uniformly mixed, followed by further addition in the flask to further react the unreacted monomer. And again after maintaining for 1 hour and finally 1 part by weight of xylene and 0.1 parts by weight of benzoyl peroxide uniformly mixed and added to react the unreacted monomer. Thereafter, 60 to 120 minutes of holding reaction was carried out to obtain a transparent oily acrylic resin having a nonvolatile content of 70% by weight, Gardner viscosity Z2 to Z5, a hydroxyl value of 62 mgKOH / g, an acid value of 14 mgKOH / g, and a glass transition temperature of 13 ° C.

Production Examples 1-3 and Comparative Production Examples 1-2

The water-soluble baking enamel coating of Preparation Examples 1 to 3 was prepared by applying the acrylic resin prepared in Synthesis Example 1 and the composition and content disclosed in Table 1 below. In addition, the oil-based baking enamel coating of Comparative Examples 1 and 2 was prepared by applying the acrylic resin prepared in Synthesis Example 2 and the compositions and contents disclosed in Table 1 below. The unit applied to the said Table 1 is a weight part.

Specifically, the calcined enamel paint is added to the materials of 1) to 6) disclosed in Table 1 in order, and then mixed to disperse to a prescribed particle size (10 μm) with a disperser. At this time, the temperature of the dispersion is adjusted to 50 ° C or less. Subsequently, the materials of 7) to 14) are added to the dispersed solution in order and then mixed.

TABLE 1

 Raw material formulation Preparation Example 1 Preparation Example 2 Preparation Example 3 Comparative Preparation Example 1 Comparative Production Example 2 1) butyl cellosolve 7 6 5 - - 2) aqueous solvent (ion exchange water) 30 28 26 - - 3) xylene - - - 37 31 4) primary amine 9 7.7 6.4 - - 5) Synthesis Example 1 Synthesis Example 2 90- 77- 64- -90 -64 6) Color Pigment 40 35 30 40 30 7) Crosslinked resin (90% solids) 10 10 10 10 10 8) Dispersant 0.5 0.5 0.5 0.5 0.5 9) Defoamer 0.4 0.4 0.4 0.4 0.4 10) Crosslinking Catalyst 0.5 0.5 0.5 - -  11) Flow control agent (A) 0.2 0.2 0.2 0.2 0.2  12) Flow control agent (B) 0.2 0.2 0.2 - - 13) Flow control agent (C) 0.15 0.15 0.15 - -  14) Auxiliary Solvent 3 3 3 - -

receptivity Sobu  Evaluation of coating properties of enamel paint

The calcined enamel paints of Preparation Examples 1 to 2 and Comparative Preparation Examples 1 and 2 were coated on a 0.8T CR plate coated with zinc phosphate to evaluate physical properties, and drying conditions were 20 minutes at 140 ° C. The results are shown in Table 2.

TABLE 2

Property item Preparation Example 1 Preparation Example 2 Preparation Example 3 Comparative Preparation Example 1 Comparative Production Example 2 Coating appearance ◎ ◎ ◎ ◎ ◎ Adhesion 100/100 100/100 100/100 100/100 100/100 Solvent resistance ◎ ◎ ◎ ◎ ◎ Boiling water resistance ◎ ◎ ◎ △ △ Alkali resistance ◎ ◎ ◎ ◎ ◎ Acid resistance ◎ ◎ ◎ △ ◎ Polish 83 86 87 82 80 Pencil hardness H H 2H F F

In Table 2,? Denotes a very good state,? Denotes a good state,? Denotes a normal state, and X denotes a poor state. The performance of the coating film was evaluated according to the following general coating material property evaluation method.

* Appearance of the film: It was coated on 0.8T CR iron plate and compared the degree of bubble, tee, flow, boiling, spot, smoothness.

* Adhesiveness: According to ASTM D3359 tape adhesion test method, the degree of peeled part was observed after the tape adhesion test in 100 1 mm × 1 mm scales.

* Solvent resistance: The state of the coating film was confirmed after 24 hours by immersion in xylene.

* Boiling water resistance: After immersion in water at 98 ± 2 ℃ for 1 hour, the state of coating was confirmed.

* Alkali resistance: After 24 hours immersion in 5% NaOH aqueous solution, the state of the coating film was confirmed.

* Acid: To determine the state of 5% CH ₃ COOH solution after 24 hours immersion in the coating film.

Gloss: 60 ^o gloss was measured using a digital gloss meter.

* Pencil hardness: The hardness of the coating film was measured using Mitsubishi Uni-pencil.

 As can be seen from the above evaluation of the physical properties, the water-soluble baking agent enamel paint of the present invention has an oil-based coating composition in terms of adhesion, hardness, coating appearance, solvent resistance, boiling resistance, chemical resistance, gloss, etc., which are required for industrial coatings. In comparison, excellent physical properties equivalent to or higher are shown.

  The water-soluble calcined enamel paint, which is an industrial paint of the present invention, may use organic pigments and other additives in a mixed resin in which proper properties are mixed with a water-soluble acrylic resin and a cross-linking melamine resin to improve the organic solvent emission problem, which is a problem of the oil paint. Can be. In addition, even when coated in a work space where the humidity can not be adjusted, it is possible to form an excellent coating film in boiling water, gloss, hardness and the like.

As described above, although described with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified without departing from the spirit and scope of the invention described in the claims below. And can be changed.

Claims (6)

Hydroxyl value 20-70 mgKOH / g, Acid value 40-65 mgKOH / g, Non-volatile content 50-70 weight%, Acrylic resin 35-60 weight% with the glass transition temperature of 0-30 degreeC, Melamine resin for crosslinking 4-10 weight %, 15 to 35% by weight colored pigment, 2 to 5% by weight primary amine, 3 to 5% by weight butyl cellosolve, dispersant for water based paints, defoamer for water based paint, crosslinking catalyst and flow control agent A water-soluble baking enamel paint comprising 0.4 to 3% by weight of an additive, 2 to 4% by weight of an auxiliary solvent, and 10 to 20% by weight of a water-soluble solvent. The water-soluble calcined enamel paint according to claim 1, wherein the crosslinking melamine resin is hexamethoxymelamine resin or modified hexamethoxymelamine resin. The water-soluble baking enamel coating according to claim 1, wherein the use ratio of the crosslinking melamine resin and the acryl resin satisfies 1: 5 to 7. The additive according to claim 1, wherein the additive comprises 0.1 to 0.5% by weight of an aqueous paint dispersant, 0.1 to 0.5 of an antifoaming agent for an aqueous paint, 0.1 to 0.5 for a crosslinking catalyst, and 0.3 to 0.1% by weight of a flow control agent. Water soluble Sobu enamel paint. 2. The crosslinking catalyst according to claim 1, wherein the crosslinking catalyst is a blocked acid catalyst having a minimum curing temperature of 80 to 100 DEG C, and the flow control agent is organoclay, bentonite, montmorillonite and inorganic clay smectite. Water-soluble baking enamel paint, characterized in that it comprises at least one selected from the group consisting of: The water-soluble calcined enamel paint according to claim 1, wherein the water-soluble solvent is ion-exchanged water, and the auxiliary solvent is a synthetic isoparaffin solvent having a minimum boiling point of 56 ° C or higher and a boiling point of 180 ° C or higher.