technical field
[One]
It relates to an electrical steel sheet and a method for manufacturing the same. More specifically, it relates to an electrical steel sheet that secures excellent adhesion and surface properties by forming different types of adhesive layers on the upper and lower surfaces of the electrical steel sheet and a method for manufacturing the same.
background
[2]
Electrical steel sheet is a product used as a material for transformers, motors, and electric machines, and is a functional product that places importance on electrical properties, unlike general carbon steel that emphasizes processability such as mechanical properties. Required electrical properties include low iron loss, high magnetic flux density, magnetic permeability and space factor.
[3]
Electrical steel sheet is further divided into grain-oriented electrical steel sheet and non-oriented electrical steel sheet. Grain-oriented electrical steel sheet is an electrical steel sheet with excellent magnetic properties in the rolling direction by forming a Goss texture ({110}<001> texture) throughout the steel sheet by using an abnormal grain growth phenomenon called secondary recrystallization. Non-oriented electrical steel sheet is an electrical steel sheet with uniform magnetic properties in all directions on the rolled sheet.
[4]
Electrical steel sheet is divided into two types, which require stress relief annealing (SRA) to improve magnetic properties after punching and omit SRA when the cost loss due to heat treatment is greater than the magnetic property effect caused by SRA. are using
[5]
On the other hand, the insulating film formation is a process corresponding to the final manufacturing process of the product. In addition to the electrical properties that normally suppress the occurrence of eddy currents, continuous punching suppresses the wear of the mold when punching it into a predetermined shape and then stacking a number of them into an iron core. After the SRA process, which recovers the workability and the magnetic properties by removing the machining stress of the steel sheet, it requires sticking resistance and surface adhesion that do not adhere between the iron core steel sheets. In addition to these characteristics, excellent coating workability of the coating solution and solution stability that can be used for a long time after mixing are also required.
[6]
In addition, an adhesive coating layer capable of bonding (fastening) electrical steel sheets without using conventional fastening methods such as welding, cramping, and interlocking is also known.
DETAILED DESCRIPTION OF THE INVENTION
technical challenge
[7]
An electrical steel sheet and a manufacturing method thereof are provided. More specifically, by forming different types of adhesive layers on the upper and lower surfaces of the electrical steel sheet, to provide an electrical steel sheet and a method of manufacturing the same for securing excellent adhesion and surface properties.
means of solving the problem
[8]
The electrical steel sheet according to an embodiment of the present invention includes an upper surface adhesive layer located on the upper surface of the electrical steel sheet and a lower surface adhesive layer located on the lower surface of the electrical steel sheet, the upper surface adhesive layer has a pencil hardness of F or less, and the lower adhesive layer has a pencil hardness of H or more am.
[9]
The upper adhesive layer includes a resin having a hydroxyl equivalent of 1 to 10 mgKOH/g, and the lower adhesive layer includes a resin having a hydroxyl equivalent of 15 to 20 mgKOH/g.
[10]
The upper adhesive layer may include a resin having a weight average molecular weight of 15,000 to 50,000, and the lower adhesive layer may include a resin having a weight average molecular weight of 1,000 to 10,000.
[11]
The upper adhesive layer may further include a curing agent in an amount of 3% by weight or less, and the lower adhesive layer may further include a curing agent in an amount of 5 to 10% by weight.
[12]
The upper adhesive layer may have a pencil hardness of F or less, and the lower adhesive layer may have a pencil hardness of H or more.
[13]
The resin may include at least one of an epoxy-based resin, a siloxane-based resin, an acrylic resin, a phenol-based resin, a styrene-based resin, a vinyl-based resin, an ethylene-based resin, an ester-based resin, and a urethane-based resin.
[14]
The curing agent may include at least one of a melamine-based curing agent, a urethane-based curing agent, an aliphatic polyamine curing agent, a modified aliphatic polyamine curing agent, an aromatic polyamine curing agent, and an organic acid anhydride-based curing agent.
[15]
The method for manufacturing an electrical steel sheet according to an embodiment of the present invention comprises the steps of: applying an upper surface adhesive composition to the upper surface of the electrical steel sheet to form an upper adhesive layer; and applying the lower adhesive composition to the lower surface of the electrical steel sheet to form a lower adhesive layer; Including, the top adhesive composition includes a resin having a hydroxyl equivalent of 1 to 10 mgKOH/g, and the bottom adhesive composition includes a resin having a hydroxyl equivalent of 15 to 20 mgKOH/g.
[16]
The upper adhesive composition may include a resin having a weight average molecular weight of 15,000 to 50,000, and the lower adhesive composition may include a resin having a weight average molecular weight of 1,000 to 10,000.
[17]
The top adhesive composition may further include a curing agent in an amount of 3% by weight or less based on 100% by weight of the solid content, and the lower adhesive composition may further include 5 to 10% by weight of a curing agent based on 100% by weight of the solid content.
[18]
In the electrical steel sheet laminate according to an embodiment of the present invention, a plurality of electrical steel sheets are laminated, and an upper surface adhesive layer and a lower surface adhesive layer are interposed in order between the electrical steel sheets.
[19]
The upper adhesive layer has a pencil hardness of F or less, and the lower adhesive layer has a pencil hardness of H or more.
[20]
The upper adhesive layer may include a resin having a weight average molecular weight of 15,000 to 50,000, and the lower adhesive layer may include a resin having a weight average molecular weight of 1,000 to 10,000.
[21]
The upper adhesive layer may further include a curing agent in an amount of 3% by weight or less, and the lower adhesive layer may further include a curing agent in an amount of 5 to 10% by weight.
[22]
The upper adhesive layer includes a resin having a hydroxyl equivalent of 1 to 10 mgKOH/g, and the lower adhesive layer includes a resin having a hydroxyl equivalent of 15 to 20 mgKOH/g.
Effects of the Invention
[23]
According to one embodiment of the present invention, excellent surface properties and adhesive strength can be secured.
Brief description of the drawing
[24]
1 is a schematic diagram of a cross-section of an electrical steel sheet according to an embodiment of the present invention.
[25]
2 is a schematic diagram of a cross-section of an electrical steel sheet laminate according to an embodiment of the present invention.
Modes for carrying out the invention
[26]
Terms such as first, second and third are used to describe, but are not limited to, various parts, components, regions, layers and/or sections. These terms are used only to distinguish one part, component, region, layer or section from another part, component, region, layer or section. Accordingly, a first part, component, region, layer or section described below may be referred to as a second part, component, region, layer or section without departing from the scope of the present invention.
[27]
The terminology used herein is for the purpose of referring to specific embodiments only, and is not intended to limit the present invention. As used herein, the singular forms also include the plural forms unless the phrases clearly indicate the opposite. As used herein, the meaning of "comprising" specifies a particular characteristic, region, integer, step, operation, element and/or component, and the presence or absence of another characteristic, region, integer, step, operation, element and/or component. It does not exclude additions.
[28]
When a part is referred to as being “on” or “on” another part, it may be directly on or on the other part, or the other part may be involved in between. In contrast, when a part refers to being “directly above” another part, the other part is not interposed therebetween.
[29]
Although not defined otherwise, all terms including technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. Commonly used terms defined in the dictionary are further interpreted as having a meaning consistent with the related technical literature and the presently disclosed content, and unless defined, are not interpreted in an ideal or very formal meaning.
[30]
Hereinafter, embodiments of the present invention will be described in detail so that those of ordinary skill in the art to which the present invention pertains can easily implement them. However, the present invention may be embodied in several different forms and is not limited to the embodiments described herein.
[31]
1 schematically shows a cross section of an electrical steel sheet according to an embodiment of the present invention. Referring to Figure 1, the structure of the electrical steel sheet according to an embodiment of the present invention will be described. The electrical steel sheet of FIG. 1 is only for illustrating the present invention, and the present invention is not limited thereto. Therefore, the structure of the electrical steel sheet can be variously modified.
[32]
As shown in FIG. 1, the electrical steel sheet according to an embodiment of the present invention includes an upper adhesive layer 20 positioned on the upper surface of the electrical steel plate 10 and a lower adhesive layer 30 positioned on the lower surface of the electrical steel plate 10.
[33]
The electrical steel sheet 10 may be a non-oriented electrical steel sheet or a grain-oriented electrical steel sheet. In an embodiment of the present invention, the alloy component of the electrical steel sheet 10 may be used without limitation. For example, the electrical steel sheet 10 is, by weight%, C: 0.1% or less, Si: 6.0% or less, P: 0.5% or less, S: 0.005% or less, Mn: 1.0% or less, Al: 2.0% or less, N: 0.005% or less, Ti: 0.005% or less, Cr: 0.5% or less, and may include Fe and unavoidable impurities as the balance.
[34]
An upper surface adhesive layer 20 is positioned on the upper surface of the electrical steel sheet 10 .
[35]
The upper adhesive layer 20 includes a resin having a hydroxyl equivalent of 1 to 10 mgKOH/g. When the resin contains an appropriate amount of hydroxyl groups, when the laminate 100 is manufactured by laminating the electrical steel sheets 10 , the adhesive force with the lower surface adhesive layer 30 can be improved. It is possible to bond electrical steel sheets without using conventional fastening methods such as welding, cramping, interlocking, etc. by improving the adhesion, and without adding deformation to the steel sheet, the magnetism is improved.
[36]
If the hydroxyl equivalent is too high, the adhesive strength with the lower adhesive layer 30 may be reduced. If the hydroxyl equivalent is too low, a defect may occur in which the upper surface adhesive layer 20 and the lower surface adhesive layer 30 are attached by coil winding after product production. More specifically, the upper adhesive layer 20 may include a resin having a hydroxyl equivalent of 3 to 5 mgKOH/g. In this case, the hydroxyl group (-OH) equivalent means the weight of the hydroxyl group (-OH) with respect to the weight of the resin, and 1 g of the dried solid is obtained from the weight of KOH required to neutralize the acid value capable of being acetylated.
[37]
The upper adhesive layer 20 may include a resin having a weight average molecular weight of 15,000 to 50,000. When a resin having an appropriate molecular weight is included, adhesion to the lower surface adhesive layer 30 may be improved. If the weight average molecular weight is too low, the adhesive force with the adhesive layer 30 may be deteriorated. If the weight average molecular weight is too high, a defect may occur in which the upper surface adhesive layer 20 and the lower surface adhesive layer 30 are attached by coil winding after product production. More specifically, the upper adhesive layer 20 may include a resin having a weight average molecular weight of 20,000 to 40,000.
[38]
The upper adhesive layer 20 may further include a curing agent in an amount of 3 wt% or less. The curing agent may be 0% by weight, ie not included. When too much curing agent is included, the adhesive strength with the adhesive layer 30 may decrease. The remainder excluding the curing agent may be a resin. More specifically, the curing agent may not be included. That is, the upper surface adhesive layer 20 may be made of only resin.
[39]
The upper adhesive layer 20 may have a pencil hardness of F or less. Here, the pencil hardness can be measured by drawing a line at a 45 degree angle with a standard pencil under a load of 500 g and visually checking the presence or absence of indentations on the surface of the coating layer. The highest hardness at which indentation does not occur is taken as the hardness of the adhesive layer. More specifically, the upper surface adhesive layer 20 may have a pencil hardness of B to F.
[40]
The kind of resin is not particularly limited. For example, the resin may include one or more of an epoxy-based resin, a siloxane-based resin, an acrylic resin, a phenol-based resin, a styrene-based resin, a vinyl-based resin, an ethylene-based resin, an ester-based resin, and a urethane-based resin. More specifically, it may include at least one of an epoxy-based resin, an ester-based resin, a urethane-based resin, and an acrylic resin.
[41]
The curing agent may include at least one of a melamine-based curing agent, a urethane-based curing agent, an aliphatic polyamine curing agent, a modified aliphatic polyamine curing agent, an aromatic polyamine curing agent, and an organic acid anhydride-based curing agent.
[42]
The aliphatic polyamine curing agent may include diethylenetriamine, triethylenetetramine, and the like. The modified aliphatic polyamine curing agent may include epoxy polyamine, oxyethylene polyamine, and the like. The aromatic polyamine curing agent may include metaphenylenediamine, diaminodiphenylmethane, diaminopediphenylsulfone, and the like. The organic acid anhydride-based curing agent may include tetrahydrophthalic anhydride and pyromellitic anhydride.
[43]
In addition to the above-mentioned resin and curing agent, it may further include a metal phosphate or a metal chroman salt.
[44]
On the lower surface of the electrical steel sheet 10, the lower surface adhesive layer 30 is located.
[45]
The lower surface adhesive layer 30 includes a resin having a hydroxyl equivalent of 15 to 20 mgKOH/g. When the resin contains an appropriate amount of hydroxyl groups, when the laminate 100 is manufactured by laminating the electrical steel sheets 10 , the adhesive force with the upper surface adhesive layer 20 can be improved. At the same time, it is possible to prevent scratch-type defects in the production line for the adhesive layer 30 . In the production of electrical steel sheet, the roll and the lower surface are in contact and are transferred. At this time, if the hydroxyl equivalent of the lower surface adhesive layer 30 is too low, a number of scratch-type defects may occur.
[46]
The lower surface adhesive layer 30 may include a resin having a weight average molecular weight of 1,000 to 10,000. When a resin having an appropriate molecular weight is included, adhesion to the upper surface adhesive layer 20 may be improved. If the weight average molecular weight is too low, the adhesive force with the upper surface adhesive layer 20 may be deteriorated. If the weight average molecular weight is too high, many scratch-like defects may occur. More specifically, the adhesive layer 30 may include a resin having a weight average molecular weight of 1,500 to 5,000. More specifically, the adhesive layer 30 may include a resin having a weight average molecular weight of 2,000 to 3,000.
[47]
The lower surface adhesive layer 30 may further include a curing agent in an amount of 5 to 10% by weight. When the curing agent is included too much, the adhesive strength with the upper surface adhesive layer 20 may be reduced. When too little curing agent is included, a number of scratch-like defects may occur. The remainder excluding the curing agent may be a resin. More specifically, it may contain 5 to 8% by weight of the curing agent.
[48]
The lower adhesive layer 30 may have a pencil hardness of H or more. Here, the pencil hardness can be measured by drawing a line at a 45 degree angle with a standard pencil under a load of 500 g and visually checking the presence or absence of indentations on the surface of the coating layer. The highest hardness at which indentation does not occur is taken as the hardness of the adhesive layer. More specifically, the adhesive layer 30 may have a pencil hardness of H to 4H. More specifically, the adhesive layer 30 may have a pencil hardness of H to 3H.
[49]
The kind of resin is not particularly limited. For example, the resin may include one or more of an epoxy-based resin, a siloxane-based resin, an acrylic resin, a phenol-based resin, a styrene-based resin, a vinyl-based resin, an ethylene-based resin, an ester-based resin, and a urethane-based resin. More specifically, it may include at least one of an epoxy-based resin, an ester-based resin, a urethane-based resin, and an acrylic resin. It may be the same as or different from the resin of the above-described upper surface adhesive layer 20 .
[50]
The curing agent may include at least one of a melamine-based curing agent, a urethane-based curing agent, an aliphatic polyamine curing agent, a modified aliphatic polyamine curing agent, an aromatic polyamine curing agent, and an organic acid anhydride-based curing agent. It may be the same as or different from the curing agent of the above-described upper surface adhesive layer 20 .
[51]
In addition to the above-mentioned resin and curing agent, it may further include a metal phosphate or a metal chroman salt.
[52]
The thickness of the upper adhesive layer 20 and the lower adhesive layer 30 may be 1 to 10 μm, respectively.
[53]
The method for manufacturing an electrical steel sheet according to an embodiment of the present invention comprises the steps of: applying an upper surface adhesive composition to the upper surface of the electrical steel sheet to form an upper adhesive layer; and applying the lower adhesive composition to the lower surface of the electrical steel sheet to form a lower adhesive layer; includes
[54]
Hereinafter, each step will be described in detail.
[55]
A top adhesive composition is applied to the top surface of the electrical steel sheet 10 to form the top adhesive layer 20 .
[56]
The top adhesive composition includes a resin having a hydroxyl equivalent of 1 to 10 mgKOH/g. When the resin contains an appropriate amount of hydroxyl groups, when the laminate 100 is manufactured by laminating the electrical steel sheets 10 , the adhesive force with the lower surface adhesive layer 30 can be improved. It is possible to bond electrical steel sheets without using conventional fastening methods such as welding, cramping, interlocking, etc. by improving the adhesion, and without adding deformation to the steel sheet, the magnetism is improved.
[57]
If the hydroxyl equivalent is too high, the adhesive strength with the lower adhesive layer 30 may be reduced. If the hydroxyl equivalent is too low, a defect may occur in which the upper surface adhesive layer 20 and the lower surface adhesive layer 30 are attached by coil winding after product production. More specifically, the top adhesive composition may include a resin having a hydroxyl equivalent of 3 to 5 mgKOH/g. In this case, the hydroxyl group (-OH) equivalent means the weight of the hydroxyl group (-OH) with respect to the weight of the resin, and 1 g of the dried solid is obtained from the weight of KOH required to neutralize the acid value capable of being acetylated.
[58]
The top adhesive composition may include a resin having a weight average molecular weight of 15,000 to 50,000. When a resin having an appropriate molecular weight is included, adhesion to the lower surface adhesive layer 30 may be improved. If the weight average molecular weight is too high, a defect may occur in which the upper surface adhesive layer 20 and the lower surface adhesive layer 30 are attached by coil winding after product production. More specifically, the top adhesive composition may include a resin having a weight average molecular weight of 20,000 to 40,000.
[59]
The top adhesive composition may further include a curing agent in an amount of 3% by weight or less based on 100% by weight of the solid content. The curing agent may be 0% by weight, ie not included. When too much curing agent is included, the adhesive strength with the adhesive layer 30 may decrease. The remainder excluding the curing agent may be a resin. More specifically, the curing agent may not be included. That is, the solid content of the top adhesive composition may be composed of only the resin. The top adhesive composition may further include a solvent in addition to the solid content. As the solvent, a general solvent used in the coating composition may be used, and a detailed description thereof will be omitted. For example, the solvent may include one or more of water and an organic solvent.
[60]
The kind of resin is not particularly limited. For example, the resin may include one or more of an epoxy-based resin, a siloxane-based resin, an acrylic resin, a phenol-based resin, a styrene-based resin, a vinyl-based resin, an ethylene-based resin, an ester-based resin, and a urethane-based resin. More specifically, it may include at least one of an epoxy-based resin, an ester-based resin, a urethane-based resin, and an acrylic resin.
[61]
The curing agent may include at least one of a melamine-based curing agent, a urethane-based curing agent, an aliphatic polyamine curing agent, a modified aliphatic polyamine curing agent, an aromatic polyamine curing agent, and an organic acid anhydride-based curing agent.
[62]
After applying the top adhesive composition, it is cured to form the top adhesive layer 20 . This step may be performed in a temperature range of 100 to 300 °C for curing the adhesive coating composition. Characteristics (hydroxyl group equivalent, weight average molecular weight) of the components in the top adhesive composition before and after curing are substantially unchanged.
[63]
The lower surface adhesive composition is applied to the lower surface of the electrical steel sheet 10 to form the lower surface adhesive layer 30 . The above-described steps of forming the upper surface adhesive layer 20 and the lower surface adhesive layer 30 may be configured irrespective of the order. That is, after the upper surface adhesive layer 20 is formed, the lower surface adhesive layer 30 may be formed, and after the lower surface adhesive layer 30 is formed, the upper surface adhesive layer 20 may be formed. It is also possible to simultaneously form the upper adhesive layer 20 and the lower adhesive layer 30 .
[64]
The lower surface adhesive composition includes a resin having a hydroxyl equivalent weight of 15 to 20 mgKOH/g. When the resin contains an appropriate amount of hydroxyl groups, when the laminate 100 is manufactured by laminating the electrical steel sheets 10 , the adhesive force with the upper surface adhesive layer 20 can be improved. At the same time, it is possible to prevent scratch-type defects in the production line for the adhesive layer 30 . In the production of electrical steel sheet, the roll and the lower surface are in contact and are transferred. At this time, if the hydroxyl equivalent of the lower surface adhesive composition is too low, a number of scratch-type defects may occur.
[65]
The lower surface adhesive composition may include a resin having a weight average molecular weight of 1,000 to 10,000. When a resin having an appropriate molecular weight is included, adhesion to the upper surface adhesive layer 20 may be improved. If the weight average molecular weight is too low, the adhesive force with the upper surface adhesive layer 20 may be deteriorated. If the weight average molecular weight is too high, many scratch-like defects may occur. More specifically, the adhesive composition may include a resin having a weight average molecular weight of 1,500 to 5,000. More specifically, the adhesive composition may include a resin having a weight average molecular weight of 2,000 to 3,000.
[66]
The lower surface adhesive composition may further include a curing agent in an amount of 5 to 10% by weight based on 100% by weight of the solid content. When the curing agent is included too much, the adhesive strength with the upper surface adhesive layer 20 may be reduced. When too little curing agent is included, a number of scratch-like defects may occur. The remainder excluding the curing agent may be a resin. More specifically, it may contain 5 to 8% by weight of the curing agent. The lower surface adhesive composition may further include a solvent in addition to the solid content. As the solvent, a general solvent used in the coating composition may be used, and a detailed description thereof will be omitted. For example, the solvent may include one or more of water and an organic solvent.
[67]
The kind of resin is not particularly limited. For example, the resin may include one or more of an epoxy-based resin, a siloxane-based resin, an acrylic resin, a phenol-based resin, a styrene-based resin, a vinyl-based resin, an ethylene-based resin, an ester-based resin, and a urethane-based resin. More specifically, it may include at least one of an epoxy-based resin, an ester-based resin, a urethane-based resin, and an acrylic resin. It may be the same as or different from the resin of the above-described top adhesive composition.
[68]
The curing agent may include at least one of a melamine-based curing agent, a urethane-based curing agent, an aliphatic polyamine curing agent, a modified aliphatic polyamine curing agent, an aromatic polyamine curing agent, and an organic acid anhydride-based curing agent. It may be the same as or different from the curing agent of the above-mentioned top surface adhesive composition.
[69]
After the lower surface adhesive composition is applied and cured, the lower surface adhesive layer 30 is formed. This step may be performed in a temperature range of 100 to 300 °C for curing of the adhesive coating composition. The characteristics (hydroxyl group equivalent, weight average molecular weight) of the components in the lower surface adhesive composition before and after curing are substantially unchanged.
[70]
2 schematically shows a cross-section of an electrical steel sheet laminate according to an embodiment of the present invention. Referring to Figure 2, the structure of the electrical steel sheet laminate according to an embodiment of the present invention will be described. The electrical steel sheet laminate of FIG. 2 is only for illustrating the present invention, and the present invention is not limited thereto. Therefore, the structure of the electrical steel sheet laminate can be variously modified.
[71]
As shown in FIG. 2 , in the electrical steel sheet laminate 100 according to an embodiment of the present invention, a plurality of electrical steel sheets 10 are laminated, and an upper surface adhesive layer 20 and a lower surface adhesive layer 30 between the electrical steel sheets 10 . ) are listed in order.
[72]
Since the electrical steel sheet 10, the upper surface adhesive layer 20, and the lower surface adhesive layer 30 are the same as the above-described electrical steel sheet 10, overlapping descriptions will be omitted.
[73]
The method for manufacturing the electrical steel sheet laminate 100 includes laminating a plurality of electrical steel sheets 10 on which an upper surface adhesive layer 20 and a lower surface adhesive layer 30 are formed, and thermally fusion. Through the heat-sealing step, the resin components in the upper adhesive layer 20 and the lower adhesive layer 30 are heat-sealed, thereby forming a heat-sealing layer.
[74]
The thermal fusion may be performed at a temperature of 100 to 300° C., a pressure of 0.05 to 5.0 Mpa, and a pressure of 0.1 to 120 minutes. Each of the above conditions may be independently satisfied, and two or more conditions may be simultaneously satisfied. As such, by controlling the temperature, pressure, and time conditions in the heat-sealing step, between non-oriented electrical steel sheets, without gaps or pores, it can be densely heat-sealed.
[75]
The heat-sealing step includes a temperature raising step and a fusion bonding step, and the temperature increase rate of the temperature raising step may be 10°C/min to 1000°C/min.
[76]
As such, the electrical steel sheet laminate according to an embodiment of the present invention not only improves the magnetic properties of the electrical steel sheet itself (specifically, iron loss, magnetic flux density, etc.), but also has excellent adhesion by the adhesive coating layer.
[77]
Hereinafter, the present invention will be described in more detail through examples. However, these examples are only for illustrating the present invention, and the present invention is not limited thereto.
[78]
Example
[79]
A specimen was prepared of a non-oriented electrical steel sheet (50 × 50 mm) containing 3.15 wt% of silicon (Si) and annealed with a plate thickness of 0.35 mm. The adhesive composition composed of the solids listed in Table 1 below is applied to each prepared blank specimen at a constant thickness on the top and bottom using a bar coater, cured at 150 to 250° C. for 20 seconds based on the plate temperature, and then cooled slowly in the air. to form an adhesive coating layer with a thickness of about 3.0 μm.
[80]
After the electrical steel sheet coated with the adhesive coating layer was laminated to a height of 20 mm, it was pressurized with a force of 0.1 MPa and heat-sealed at 120° C. for 10 minutes. The adhesive force of the heat-sealed electrical steel sheet for each condition was measured by the shear tension method.
[81]
Adhesion : After fixing the specimen produced by shear strength to an upper/lower jig (JIG) with a constant force, it was measured using a device for measuring the tensile force of the laminated sample while pulling it at a constant speed. In this case, in the case of the shear method, the measured value was measured at the point where the interface with the minimum adhesive force among the interfaces of the laminated samples fell off.
[82]
Surface hardness : As a method of measuring the surface hardness of the coating layer, a pencil hardness measurement method is used. Using a standard pencil (Mitsubishi Pencil, 8B ~ 10H) with a load of 500 g, draw a line at an angle of 45 degrees to visually check for indentations on the surface of the coating layer.
[83]
[Table 1]
[84]
[Table 2]
[85]
As shown in Tables 1 and 2, it can be confirmed that Examples 1 and 2 have excellent surface properties and adhesion.
[86]
On the other hand, as in Comparative Example 1, when the upper and lower surfaces are soft and have the same hydroxyl equivalent, molecular weight, curing agent content and hardness, the shear adhesion after heat sealing is excellent, but the surface hardness of the coating layer on the lower surface is poor, so there are many scratch-type defects. can be confirmed to have occurred.
[87]
As in Comparative Example 2, when the upper and lower surfaces of the hard furnace were configured to have the same hydroxyl equivalent, molecular weight, curing agent content, and hardness, scratch-type defects did not occur, but the shear adhesion after heat sealing was poor.
[88]
As in Comparative Example 3, when the properties of the adhesive layer on the upper and lower surfaces were reversed, the shear adhesion after heat sealing was excellent, but it was confirmed that a number of scratch-type defects occurred due to the poor surface hardness of the coating layer on the lower surface.
[89]
As in Comparative Example 4, when the hardness of the adhesive layer was excessively increased, scratch-type defects did not occur, but the shear adhesion after heat sealing was poor.
[90]
When the hardness of the upper surface adhesive layer was too low as in Comparative Example 5, a defect occurred in which the upper and lower adhesive layers were attached by coil winding after product production.
[91]
The present invention is not limited to the embodiments, but can be manufactured in various different forms, and those of ordinary skill in the art to which the present invention pertains can use other specific forms without changing the technical spirit or essential features of the present invention. It will be appreciated that this may be practiced. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.
[92]
[Explanation of code]
[93]
10: electrical steel sheet
[94]
20: top adhesive layer
[95]
30: lower surface adhesive layer
[96]
40: electrical steel sheet laminate
Claims
[Claim 1]
An electrical steel sheet comprising an upper surface adhesive layer located on the upper surface of the electrical steel sheet and a lower surface adhesive layer located on the lower surface of the electrical steel sheet, wherein the upper surface adhesive layer has a pencil hardness of F or less, and the lower surface adhesive layer has a pencil hardness of H or more.
[Claim 2]
The electrical steel sheet according to claim 1, wherein the upper adhesive layer includes a resin having a weight average molecular weight of 15,000 to 50,000, and the lower adhesive layer includes a resin having a weight average molecular weight of 1,000 to 10,000.
[Claim 3]
The electrical steel sheet according to claim 1, wherein the upper adhesive layer further comprises a curing agent in an amount of 3 wt% or less, and the lower adhesive layer further comprises a curing agent in an amount of 5 to 10 wt%.
[Claim 4]
The electrical steel sheet according to claim 1, wherein the upper adhesive layer includes a resin having a hydroxyl equivalent of 1 to 10 mgKOH/g, and the lower adhesive layer includes a resin having a hydroxyl equivalent of 15 to 20 mgKOH/g.
[Claim 5]
According to claim 1, wherein the resin included in the upper adhesive layer and the lower adhesive layer is an epoxy-based resin, a siloxane-based resin, an acrylic resin, a phenol-based resin, a styrene-based resin, a vinyl-based resin, an ethylene-based resin, an ester-based resin and Electrical steel sheet containing at least one type of urethane-based resin.
[Claim 6]
The curing agent according to claim 3, wherein the curing agent included in the upper adhesive layer and the lower adhesive layer includes at least one of a melamine-based curing agent, a urethane-based curing agent, an aliphatic polyamine curing agent, a modified aliphatic polyamine curing agent, an aromatic polyamine curing agent, and an organic acid anhydride-based curing agent, respectively. electric steel plate.
[Claim 7]
Including; forming an upper surface adhesive layer by applying an upper surface adhesive composition to the upper surface of the electrical steel sheet; and applying the lower surface adhesive composition to the lower surface of the electrical steel sheet to form a lower surface adhesive layer; wherein the upper surface adhesive composition has a hydroxyl equivalent of 1 to 10 mgKOH/g of a resin, and the lower surface adhesive composition is a method of manufacturing an electrical steel sheet comprising a resin having a hydroxyl equivalent of 15 to 20 mgKOH/g.
[Claim 8]
The method of claim 7, wherein the upper adhesive composition comprises a resin having a weight average molecular weight of 15,000 to 50,000, and the lower adhesive composition includes a resin having a weight average molecular weight of 1,000 to 10,000.
[Claim 9]
The method according to claim 7, wherein the upper surface adhesive composition further comprises 3% by weight or less of a curing agent based on 100% by weight of the solid content, and the lower surface adhesive composition further contains 5 to 10% by weight of the curing agent based on 100% by weight of the solid content. A method of manufacturing an electrical steel sheet comprising.
[Claim 10]
A plurality of electrical steel sheets are laminated, and the upper surface adhesive layer and the lower surface adhesive layer are interposed in order between the electrical steel sheets, the upper surface adhesive layer has a pencil hardness of F or less, and the lower surface adhesive layer has a pencil hardness of H or more.
[Claim 11]
The electrical steel sheet laminate according to claim 10, wherein the upper adhesive layer includes a resin having a weight average molecular weight of 15,000 to 50,000, and the lower adhesive layer includes a resin having a weight average molecular weight of 1,000 to 10,000.
[Claim 12]
The electrical steel sheet laminate according to claim 10, wherein the upper adhesive layer further comprises a curing agent in an amount of 3 wt% or less, and the lower adhesive layer further comprises a curing agent in an amount of 5 to 10 wt%.
[Claim 13]
The electrical steel sheet laminate according to claim 10, wherein the upper adhesive layer includes a resin having a hydroxyl equivalent of 1 to 10 mgKOH/g, and the lower adhesive layer includes a resin having a hydroxyl equivalent of 15 to 20 mgKOH/g.