JP2006096881A - Powder adhesive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a powder adhesive having coating property which imparts a coating film with a proper thickness enough for stable temporal tacking of a small surface material to be processed, temporal tacking property and having an excellent adhesion. <P>SOLUTION: The invention relates to the powder adhesive comprising (a) a powder mainly comprising a ceramic based resin with 0.1-350 μm of particle diameter containing at least one of (b) a plasticizer with 40-100°C of melting point and 0.1-350 μm of particle diameter and/or a powder of (a higher aliphatic acid with ≥14C and/or ≥16C higher alcohol), and (c) a powder with average particle diameter of 0.1-30 μm of an inorganic powder and/or a powder of a crosslinkable polymer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a powder adhesive that temporarily fixes a material to be processed when cutting, cutting and polishing materials such as glasses and magnetic materials used in electronic parts and optical devices. Is excellent in applicability and temporary fixability due to its micro-foaming property, and in particular, the adhesive surface has a very small area, such as those having surface irregularities, or spherical, elliptical, cylindrical, etc. Or a powder adhesive having excellent temporary fixability to a material processed into a shape having a relatively small adhesion area such as a point or a line contact (hereinafter simply referred to as a small adhesion area processing material) .

  Conventionally, cutting processing of materials such as thin plates, rods or cylinders, such as glass, does not damage the material during processing, and does not move the material during processing in order to process accurately and accurately It is necessary to temporarily fix it to the workpiece. As a temporary fixing method of the above material, a liquid type adhesive in which an adhesive resin is dissolved in an organic solvent or an aqueous solution is used for a support base for fixing the material, and a spray, a brush, a spin coater, or the like is used. A solid type adhesive formed into a shape is melted by heat and applied by hand coating or the like, and the material is adhered to the support through the adhesive and cut. This processing can be performed by bundling a single material or a certain quantity of materials. After the processing is completed, the processed product is obtained by removing the adhesive adhering to the material with a cleaning agent or the like.

  Most of the liquid type adhesives used in the above processing contain an organic solvent, and the environmental load such as volatilization of the organic solvent is applied during the application work, compared to solid adhesives. Since a sufficient coating thickness cannot be obtained, the adhesive strength is weak and the temporary fixability is inferior, so that there is a problem that the material's cutting processability is lowered. In particular, the temporary fixability and the adhesive strength for the small-bond-area processed material are not good. In addition, the liquid type adhesive has a problem that workability is lowered because a step of drying the solvent or moisture after application is required.

  The solid adhesive is applied to a solid support that has been molded into a certain shape such as a rod by pressing it onto a heated support fixture and melted it to adhere to the material to be processed. Since the melt viscosity changes depending on the temperature condition, the coating thickness tends to vary. Moreover, since the melt viscosity is higher than that of the liquid adhesive, the coating workability is lowered. Furthermore, sufficient adhesive force may not be obtained with respect to the small-bond-area processed material.

  The solid-type adhesive is produced by heating a resin component constituting the adhesive to a softening point or higher, sufficiently uniformly kneading with an appropriate melt viscosity, cooling and solidifying, or the above resin component Is dissolved in an organic solvent, dried while heating or dried under reduced pressure to remove the solvent, and the resulting dried product is placed in a mold such as silicone and melted above the melting temperature of the resin. To do. In particular, when a shellac resin having thermosetting properties is used as an adhesive component, the thermosetting of the shellac resin proceeds with time depending on the heating temperature and the heating time at the time of heating and melting in the preparation of the adhesive. For this reason, since the obtained solid-type adhesive is thermosetting, the melt viscosity at the time of use is increased, so that the applicability is lowered or the adhesive strength is lowered. In addition, since the thermosetting is in progress, when the adhesive attached to the material is removed with a cleaning agent after the cutting process to produce a product, the cleaning and removability of the adhesive is deteriorated. For the purpose of solving these problems, a solid adhesive (Patent Document 1) in which rosin is blended with shellac resin is disclosed (Patent Document 1), but the adhesive is similar to the above-described solid adhesive. When the bonding area processed material is temporarily fixed, sufficient applicability and temporary tackiness are inferior. In particular, if the amount of the shellac resin is too large, the coatability is poor, and the heat-curing of the shellac resin is proceeding during the preparation of the adhesive, so that the original adhesive strength of the shellac resin is difficult to obtain.

  In addition, the above solid-type adhesive needs to be heated and melted at a high temperature at the time of preparation of the adhesive. Further, in the bonding operation, the molded solid adhesive must be remelted and applied to the adherend. It consumes high energy.

  As described above, the adhesive used for conventional temporary fixing is not suitable for temporary fixing with respect to the small-bonding-area processed material, and sufficient adhesive force cannot be obtained. In particular, a thermosetting solid adhesive has a high heat melt viscosity at the time of application due to the fact that the thermosetting progresses over time depending on the heating temperature and heating time at the time of heat melting in the preparation of the adhesive. It decreases or the adhesive strength decreases. Furthermore, since the thermosetting is in progress, the cleaning / removability of the adhesive is reduced when the adhesive attached to the material is removed with a cleaning agent after the cutting or cutting process to produce a product. There are problems such as.

  For this reason, it has an applicability with an appropriate adhesive application thickness, stable temporary fixability and adhesive strength for the above-mentioned small adhesion area processed material, and hardly changes with time even during preparation of the adhesive. In addition, there is a demand for an adhesive capable of stable temporary fixing with less work environment load in the adhesive application work.

Japanese Unexamined Patent Publication No. 7-179842

  Accordingly, an object of the present invention is to provide a coating property, a temporary fixing property, and an adhesive force having an appropriate coating thickness capable of temporarily fixing the processed material stably at the time of temporary fixing, particularly for a small bonding area processed material. It is to provide an excellent powder adhesive.

  The above object is achieved by the present invention described below. That is, the present invention is a powder adhesive comprising a powder (a) whose main component is a shellac resin having a particle size of 0.1 μm to 350 μm, and further has a melting point of 40 ° C. to 100 ° C. A powder (b) which is a plasticizer powder having a particle size of 0.1 μm to 350 μm and / or (a higher fatty acid having 14 or more carbon atoms and / or a higher alcohol having 16 or more carbon atoms) powder at a temperature of 0.1 ° C. It contains at least one powder selected from the group consisting of an inorganic powder having an average particle size of 0.1 μm to 30 μm and / or a powder (c) which is a crosslinkable polymer powder. A powder adhesive is provided.

  As a result of intensive studies to solve the above problems, the present inventor applied the above-mentioned adhesive in powder form, and then heated at 130 ° C. to 180 ° C., preferably 130 ° C. to 150 ° C. By melting, foaming due to air or moisture contained in the adhesive powder is expressed, and an apparent appropriate coating thickness can be provided. Because of this, it is excellent in applicability, temporary fixability and adhesive strength with respect to the above-mentioned small adhesion area processed material, and there is little work environment load due to solvents, etc., and there is no heating and melting step when preparing the adhesive It has been found that there is little change over time during the preparation and storage of the adhesive, and that it is easy to remove the used adhesive with a cleaning agent after processing.

  According to the present invention, by using a powder adhesive composed of powder (a) whose main component is a shellac resin having a particle size of 0.1 μm to 350 μm, the powder adhesive is bonded. Powders that sometimes have fine foaming properties, and are excellent in applicability, temporary fixability, and adhesive strength, and are particularly effective for temporary fixing during cutting, cutting, and polishing of the above-mentioned small bonding area processed materials. A body adhesive is provided.

  Next, the present invention will be described in more detail with reference to preferred embodiments. The powder (a) characterizing the present invention is a powder having a particle diameter of 0.1 μm to 350 μm, preferably a powder having a particle diameter of 70 μm to 250 μm, which has been pulverized by a known method. The powder (a) may be a shellac resin powder alone, or a shellac resin powder, a rosin resin powder having a particle size of 0.1 μm to 350 μm, an organic solvent and / or an alkali. It may be a mixture with at least one selected from resin powder soluble in a solution.

  In the powder (a) in the adhesive of the present invention, the content of the shellac resin is 40% by mass to 100% by mass, preferably 60% by mass to 100% by mass. If the content of the shellac resin increases, the adhesive strength increases, but if it is less than 40% by mass, the adhesive strength tends to decrease.

  When the above powder (a) is coarser than the particle size of 350 μm, it is estimated that the fine foaming phenomenon is reduced when the obtained powder adhesive is applied and heated and melted. It is difficult to obtain the coating thickness of the agent, and the coating property, temporary fixability, and adhesive strength to the small adhesion area processed material are inferior, and the material is easy to move when the above material is cut and difficult to perform precise cutting.

  The above shellac resin is obtained by purifying a resinous substance secreted by the shellworm by a known solution extraction method, soda method or the like, and the resin content thereof is such as aleuric acid, jaralic acid, laxialaric acid, etc. A natural shellac resin or a synthetic shellac resin mainly composed of an ester compound with a resin acid. Examples of the shellac resin include purified shellac resin, bleached shellac resin, decolorized shellac resin, and shellac resin blended with a thermosetting inhibitor. The shellac resin used in the present invention is a powder obtained by processing the above shellac resin into a particle diameter of 0.1 μm to 350 μm, preferably 70 μm to 250 μm, by a known method.

  When the particle size of the shellac resin is coarser than 350 μm, air and moisture contained in the powder layer can easily escape when the resulting powder adhesive is applied and melted by heat. Occasionally, micro-foaming is difficult to occur, and the adhesive layer surface tends to be rough, and the adhesiveness tends to decrease.

  As the shellac resin, those having a thermosetting time of 90 seconds to 600 seconds at 170 ° C. are preferably used. If the heat curing time of the shellac resin exceeds the upper limit, the adhesive strength is reduced. On the other hand, if the heat curing time is less than the lower limit, the heat curing of the shellac resin proceeds excessively, and after processing. There is a tendency that the cleaning and removing property of the adhesive is poor. The thermosetting time of the shellac resin is a measured value of the shellac resin according to JIS standard K5909.

  Examples of the rosin resin powder having the above particle diameter include powders of natural rosins and synthetic rosins by a known method. Examples of the rosins include natural rosins such as gum rosin and wood rosin; rosin ester, hydrogenated rosin, hydrogenated rosin ester, polymerized rosin, polymerized rosin ester, maleic acid modified rosin, maleic acid modified rosin ester, rosin modified Synthetic rosins such as phenol resins and mixtures thereof. When the particle diameter of the rosin-based resin powder is coarse, fine foaming hardly occurs in the molten layer when the applied powder layer is melted. As said rosin-type resin powder, what has a particle size of 0.1 micrometer-350 micrometers, Preferably it has a particle size of 70 micrometers-250 micrometers is used.

  The rosin-based resin powder preferably has a softening point of 70 ° C to 180 ° C. When the above softening point is less than 70 ° C., the adhesiveness tends to increase, so that it is difficult to pulverize, and the obtained adhesive is easily solidified during storage. The uniform applicability of is poor.

  Examples of the resin powder soluble in the organic solvent and / or alkali solution include, for example, an alkali-soluble epoxy resin powder having a carboxyl group in the molecule, an alkali-soluble acrylic resin powder, and a terpene phenol type. Resin powder etc. are mentioned. The resin powder having a softening point of 70 ° C. to 180 ° C. is preferably used. When the above softening point is less than 70 ° C., the adhesiveness tends to increase, so that it is difficult to pulverize, and the obtained adhesive is easily solidified during storage. The uniform coatability of is poor. In addition, the said softening point is a measured value based on the ring and ball method of JISK2207.

  In addition, the adhesive of the present invention includes the powder (a), the powder (b), and a powder in order to impart appropriate adhesive force and applicability to the obtained powder adhesive. It contains at least one selected from the body (c). The powder (b) is a plasticizer powder having a melting point of 40 ° C. to 100 ° C. and a particle diameter of 0.1 μm to 350 μm and / or (a higher fatty acid having 14 or more carbon atoms and / or 16 or more carbon atoms). Higher alcohol) powder, preferably having a particle size of 70 μm to 250 μm. In addition, said melting | fusing point is a measured value based on JISK3331.

  The plasticizer powder in the powder (b) is a plasticizer powder that is solid at room temperature. For example, phthalate esters such as dicyclohexyl phthalate and dimethyl isophthalate, and phosphoric acid such as triphenyl phosphate. Ester-based and other benzoic acid ester-based compounds such as triphenyl phosphate and dicyclohexyl phthalate are preferable.

  The above (higher fatty acid having 14 or more carbon atoms and / or higher alcohol having 16 or more carbon atoms) powder is a powder that is solid at room temperature, for example, myristic acid, palmitic acid, stearic acid, behenic acid. And higher alcohols such as stearyl alcohol and behenyl alcohol. The powder is preferably a higher fatty acid having 14 to 22 carbon atoms and / or a higher alcohol having 16 to 26 carbon atoms.

  The powder (c) is an inorganic powder and / or a crosslinkable polymer powder having an average particle size of 0.1 to 30 μm, preferably a powder having an average particle size of 5 to 10 μm. Examples of the powder (c) include barium sulfate such as arsenic barium sulfate and precipitated barium sulfate, inorganic powder such as calcium carbonate, aluminum silicate, silica, alumina, and titanium oxide, and crosslinkable acrylic resin. The crosslinkable polymer powder is preferably used.

  A preferable blending ratio when blending the powder (a) and the powder (b) is a / b = 50/50 to 95/5 (mass ratio). If the proportion of the powder (b) is too large, the adhesive strength of the resulting adhesive is reduced, and the microfoaming property is reduced, so that the apparent thickness of the adhesive layer cannot be obtained. On the other hand, when the proportion of the powder (b) is too small, the adhesiveness is lowered or the melt viscosity at the time of application is increased, so that workability is lowered.

  Further, when the powder (a), the powder (b) and the powder (c) are blended, the blending ratio is preferably (a + b) / c = 30/70 to 95 in the above-mentioned a / b blending ratio. / 5 (mass ratio). When there are too many compounding ratios of the said powder (c), adhesive force and microfoaming property will fall easily. On the other hand, if the blending ratio of the powder (c) is too small, the adhesive strength is lowered.

  In the present invention, an inorganic or organic foaming agent can be further blended in order to reinforce the fine foamability of the obtained powder adhesive. The blending amount is not particularly limited as long as it does not interfere with the object of the present invention. Examples of the foaming agent include foaming agents such as sodium hydrogen carbonate, ammonium carbonate, azo compounds, nitroso compounds, and sulfonylhydrazine compounds.

  In the powder adhesive of the present invention, the powder (a) is uniformly mixed and dispersed with a known powder kneader together with at least one selected from the powder (b) and the powder (c). To a powder having a particle size of 0.1 μm to 350 μm, preferably 70 μm to 250 μm. The softening point of the prepared powder adhesive is preferably 60 ° C. to 120 ° C. (measured value based on the ring and ball method of JIS K2207). When the obtained powder adhesive is coated and heat-melted when the particle size of the powder is too coarse, air and moisture contained in the powder layer are likely to escape and micro-foaming is difficult to occur. On the other hand, the surface of the layer tends to be rough, and on the other hand, if the particle size is too small, it is difficult to obtain an apparent coating thickness. The particle size of the powder adhesive of the present invention is preferably such that it has a porosity sufficient to cause fine foaming between the powder layers when the powder layer is melted by heat.

  In addition, the preparation method of the powder having the particle size range of the powder (a), the powder (b) and the powder adhesive is, for example, when obtaining a powder having a particle size of 70 μm to 250 μm. Use a sieve having a mesh corresponding to the upper limit particle size to primary screen the prepared powder, and then use a sieve to remove the powder below the lower limit particle size. The powder obtained by primary sieving is subjected to secondary sieving to prepare a powder. In addition, when it contains the microparticles | fine-particles which are out of the measurement range of screening like 0.1 micrometer-350 micrometers, the said powder is obtained by sifting using the sieve which has a mesh equivalent to an upper limit particle size. The sieve used is a standard sieve according to JIS Z8801.

  Examples of a preferable method for temporarily fixing a material to be cut and machined using the powder adhesive of the present invention include the following methods (A), (B), and (C). (A) The method includes the following steps (1) to (5). First, the powder adhesive of the present invention is applied to a temporary fixing base made of a carbon material obtained by heating the above material to 130 ° C. to 180 ° C. (1), applying finely foamed powder in the powder layer while thermally melting the applied powder adhesive (2), and then on the finely foamed adhesive Step (3) for pressing and fixing the above-mentioned material and temporarily fixing and bonding, Step (4) for cutting and cutting the temporarily fixed material with a diamond cutter, etc., and then an organic solvent or an alkaline cleaning agent The step (5) of washing and removing the above adhesive.

  In addition, as the method (B), in the step (1) in the method (A), a stick-shaped solid adhesive mainly composed of shellac resin is manually applied to the heated temporary fixing base. The material to be processed is temporarily fixed in the same manner as in the method (A) except that the primary application is performed while melting and then the powder adhesive of the present invention is applied.

  Further, as the method (C), in the step (1) in the method (A), the temporary fixing base is not preheated and applied by uniformly sprinkling the powder adhesive of the present invention. Next, the above-mentioned material to be processed is pressed against the upper surface of the powder adhesive, and then the temporary fixing base is heated to 130 ° C. to 180 ° C. to generate fine foam in the powder layer. The material to be processed is temporarily fixed in the same manner as in the method (A) except for fixing and bonding.

  The powder adhesive of the present invention is preferably used by heating the applied powder adhesive to 130 ° C. to 180 ° C. and finely foaming when melted in the above-described temporary fixing method. The powder adhesive of the invention can be temporarily fixed at about 100 ° C. to 130 ° C. without heating and melting and fine foaming.

  The materials to be cut and cut include ferrites used for electronic parts and the like, magnetic materials made of neodymium and rare earth metals, optical parts, glasses used for medical parts, etc., ceramics, A metal etc. are mentioned.

  Next, the present invention will be described more specifically with reference to examples and comparative examples. In the text, “part” or “%” is based on mass unless otherwise specified. In addition, this invention is not limited to the following Example.

[Examples 1 to 5]
The following powder (a), powder (b) and powder (c) were used and blended as shown in Table 1, and mixed and dispersed uniformly using a powder mixing and dispersing machine. Body adhesives K1 to K5 were prepared.

In addition, the powder (a), powder (b), and powder (c) in Table 1 are as follows.
Powder (a):
A1: Purified shellac resin powder having a particle size of 0.1 μm to 250 μm (thermosetting time is 300 seconds at 170 ° C.)
A2: 90% of purified shellac resin powder having a particle size of 0.1 μm to 250 μm (thermosetting time is 170 seconds at 170 ° C.), softening point, having a particle size of 0.1 μm to 250 μm Is a mixture of 10% rosin resin powder at 130 ° C. a3: 60% purified shellac resin powder having a particle size of 70 μm to 250 μm (heat curing time is 170 seconds at 170 ° C.) and 70 μm to 250 μm 40% rosin resin powder having a particle size and a softening point of 130 ° C. (b):
B1: dicyclohexyl phthalate powder having a particle size of 0.1 μm to 250 μm b2: stearic acid powder having a particle size of 70 μm to 250 μm b3: stearyl alcohol powder having a particle size of 0.1 μm to 250 μm Powder (c): Barium sulfate having an average particle diameter of 5 μm to 10 μm (barium sulfate barium sulfate)

[Comparative Example 1]
The following components were uniformly dissolved and dispersed in an organic solvent to prepare a liquid adhesive L1 as a comparative example.
・ Rosin resin 30 parts ・ Mixed solvent 70% of toluene 50% and isopropyl alcohol 70 parts

[Comparative Example 2]
The following components were homogenized by uniformly hot-melting and kneading for 10 minutes under the conditions of 120 ° C., poured into a mold after homogenization, and cooled and solidified to room temperature to prepare a comparative solid adhesive L2. .
・ 80 parts of shellac resin having a thermosetting time of 90 seconds at 170 ° C. ・ 20 parts of tricresyl phosphate

For each of the adhesives obtained above, a cylindrical magnetic body is used, and the cylindrical surface is bonded to the carbon plate temporary fixing base by the following method using the respective adhesives. The magnetic material was cut with a diamond cutter at room temperature, and its coating property, temporary fixability and adhesive strength were evaluated by the following measuring methods. The evaluation results are shown in Table 2.
[Temporary fixing adhesion]
The temporary fixing with the adhesive of the present invention is temporarily fixed and bonded at 150 ° C. by the method (A) of the temporary fixing method, and the temporary fixing with the liquid type adhesive of Comparative Example 1 is applied to the brush. After the solvent is dried, the carbon plate is heated to 150 ° C. to temporarily fix the magnetic body, and the solid adhesive of Comparative Example 2 is a carbon plate heated to 150 ° C. It is applied to the temporary fixing base by hand coating, and the magnetic material is temporarily fixed and bonded immediately.

(Applicability)
The state of applicability of the adhesive to the cylindrical surface of the magnetic body in temporary fixing was evaluated by the following evaluation method.
○: Adhesive is adhered from the contact point to the adhesion surface of the cylindrical surface of the magnetic body to the periphery of the cylinder, and sufficient adhesive applicability for temporary fixing is obtained.
X: The cylindrical surface of the magnetic material is attached only at the contact point through the adhesive surface and the adhesive, and sufficient adhesive applicability for temporary fixing is not obtained.

(Adequacy for temporary fixing)
The suitability of the cylindrical magnetic material for temporary fixing was evaluated by the following evaluation method.
○: The adhesive layer has micro-foaming, the contact area between the adhesive layer on the temporary fixing base and the cylindrical surface of the magnetic body is increased, and the temporary fixing that is sufficient to cut the magnetic body satisfactorily. Have.
Δ: The adhesive layer has no micro-foaming property, the contact area between the adhesive layer on the temporary fixing base and the cylindrical surface of the magnetic body is not sufficiently large, and the temporary cutting to such an extent that the magnetic body can be satisfactorily cut. There is no stop.
X: No microfoaming property was observed in the adhesive layer, and the adhesive layer on the temporary fixing base and the cylindrical surface of the magnetic material were bonded only by the contact, and the magnetic material could not be cut well and temporarily fixed. Is insufficient.

(Adhesive strength)
Each adhesive obtained above is applied to one stainless steel substrate, heated and melted at 150 ° C., and then the other stainless steel substrate is bonded, cooled to room temperature, and then the shearing force of the bonded substrate is applied. It measured based on the tensile shear force of JISK6850 using the tensile strength measuring machine.

  From the above evaluation results, it can be seen that the powder adhesive of the present invention is excellent in applicability, temporary fixability, and adhesive strength as a temporary fixing adhesive with respect to a small bonding area processing material such as a cylindrical shape. Proven. In addition, although this invention was demonstrated regarding adhesion | attachment of a small adhesion area processing material, the adhesive agent of this invention is not limited to the said use, It is useful also for other various adhesion | attachment.

  According to the present invention, the powder adhesive of the present invention has a fine foaming property and is excellent in applicability, temporary fixability and adhesive strength, and in particular, a small adhesive area used for electronic components and optical equipment. It can be effectively used as an adhesive for temporary fixing such as cutting, cutting and polishing of a processed material.

Claims (14)

  The powder (a) whose main component is a shellac resin having a particle size of 0.1 μm to 350 μm is a plasticizer powder having a melting point of 40 ° C. to 100 ° C. and a particle size of 0.1 μm to 350 μm and / or Or (a higher fatty acid having 14 or more carbon atoms and / or higher alcohol having 16 or more carbon atoms) powder (b), an inorganic powder having an average particle size of 0.1 μm to 30 μm and / or a high crosslinkability A powder adhesive comprising at least one selected from powder (c) which is a molecular powder.   The powder adhesive according to claim 1, wherein the particle size is 0.1 µm to 350 µm, and the softening point is 60 ° C to 120 ° C.   The powder adhesive according to claim 1, wherein the content of the shellac resin in the powder (a) is 40% by mass to 100% by mass.   The powder adhesive according to claim 1, wherein the shellac resin has a thermosetting time of 90 seconds to 600 seconds at 170 ° C.   In the powder (a), other than the shellac resin powder, a rosin resin powder having a particle size of 0.1 μm to 350 μm or a resin powder soluble in an organic solvent and / or an alkali solution is selected. The powder adhesive according to claim 1, which is at least one kind.   The powder adhesive according to claim 5, wherein a softening point of the rosin resin powder and a resin powder soluble in an organic solvent and / or an alkali solution is 70 ° C to 180 ° C.   The powder adhesive according to claim 1, wherein a blending ratio of the powder (a) and the powder (b) is a / b = 50/50 to 95/5 (mass ratio). .   The blending ratio of blending the powder (a) and the powder (b) with the powder (c) is (a + b) / c = 30/70 to 95/5 (mass ratio). The powder adhesive according to claim 1.   The powder adhesive according to claim 1, wherein the plasticizer powder is triphenyl phosphate and / or dicyclohexyl phthalate.   The powder adhesive according to claim 1, wherein the inorganic powder is at least one selected from barium sulfate, calcium carbonate, aluminum silicate, silica, alumina, and titanium oxide.   The powder adhesive according to claim 1, wherein the crosslinkable polymer powder is a crosslinkable acrylic resin powder.   Furthermore, the powder adhesive of Claim 1 which mix | blended the foaming agent.   The powder adhesive according to claim 1, wherein the material to be bonded is at least one selected from magnetic materials, glasses, metals, and ceramics.   A bonding method comprising: bonding the material to be bonded by heating and melting the powder adhesive according to claim 1 at 100 to 180 ° C.