JP5322140B2 - Mold regeneration sheet - Google Patents

Description

  The present invention relates to a mold regeneration sheet used for cleaning a mold surface of a molding mold.

  In the step of resin-sealing a semiconductor element by transfer molding, resin molding using a mold is usually repeated. As the number of repetitions (the number of shots) increases, dirt such as components, flashes, and dust that have exuded from the resin accumulate on the mold surface, particularly the cavity surface. Such dirt deteriorates the releasability when the molded product is taken out from the mold, and causes rough skin on the surface of the molded product. Therefore, the mold surface (cavity surface) of the mold is cleaned every fixed number of molding repetitions (number of shots).

As this cleaning method, a method using a cleaning sheet has been proposed (see, for example, Patent Document 1). In this method, the cleaning sheet is clamped in a state where the cleaning sheet is sandwiched between the upper mold and the lower mold, the cleaning sheet is filled into the cavity, and the cleaning sheet is heated and molded in this state. In this method, dirt is attached, and then the cleaning sheet is removed from the mold surface (cavity surface) together with the cleaning sheet.
Japanese Patent Laid-Open No. 2004-130819

  However, even if the cleaning sheet is used, dirt may not be removed depending on the shape and size of the cavity. This is because the air in the cavity is difficult to escape, and in such a case, the air reservoir is not filled with the cleaning sheet.

  Therefore, the present inventor has conducted research on the cause of the above air accumulation. As a result, the inventors have found that the cause is that the surface of the cleaning sheet has a uniform planar shape. That is, if the surface of the cleaning sheet is a uniform flat surface, when the cleaning sheet is sandwiched between the upper mold and the lower mold, the cleaning sheet covers the entire opening of the cavity, Even if the mold is clamped in this state, the air in the cavity is difficult to escape.

  Then, the present inventor has proposed and filed an application for a mold regeneration sheet that makes it easy for air to escape from the cavity based on the results of investigation of the cause of the above air accumulation (see Japanese Patent Application No. 2006). 19638). This mold recycling sheet is formed by arranging a plurality of ridges or the like side by side with a mold cleaning material made of an unvulcanized rubber composition on one side or both sides of a paper sheet or fabric sheet. An air venting gap is formed between the protrusions and the like. When this mold regeneration sheet is used to clean the mold surface (cavity surface), the contact surface between the tops of the ridges and the like and the mold surface (cavity surface) gradually expands. Since the cleaning material is filled in the cavity, the air in the cavity is vented in the meantime, so that the mold cleaning material can reach all corners of the cavity and clean the entire inside of the cavity.

  However, even when the air gap is formed between the adjacent ridges and the like, when the cavity volume is large, the mold surface (cavity surface) of the mold is cleaned. It has been found that air venting in the cavity may become inadequate, which causes the mold cleaning material to cease to spread throughout the cavity.

  The present invention has been made in view of such circumstances, and provides a mold regeneration sheet that makes it easy to escape air from the cavity even when the volume of the cavity is large, and exhibits excellent filling properties. For that purpose.

In order to achieve the above object, the mold regeneration sheet of the present invention is a mold regeneration sheet used for cleaning the mold surface of the mold, and has a basis weight of 70 to 600 g / m ² . A mold cleaning material made of an unvulcanized rubber-based composition or a thermosetting resin-based composition on one or both sides of a non-woven fabric serving as a substrate having a thickness in the range of 0.1 to 3.0 mm. A pattern of a predetermined raised shape having a void for air venting is formed, and the nonwoven fabric as a base material is exposed from the air venting void of the pattern, and the exposed nonwoven fabric portion is a gap between the fibers of the nonwoven fabric. Utilizing the structure, it is formed in the air intake portion when the mold surface of the mold is cleaned.

The present inventor has further studied to make it easy for air in the cavity to escape even when the volume of the cavity is large. In the process, a mold cleaning material made of an unvulcanized rubber-based composition or a thermosetting resin-based composition is formed into a pattern having a raised shape on one or both sides of the nonwoven fabric. Focusing on taking air into the gaps between the fibers of the nonwoven fabric from where the nonwoven fabric was not formed, further research was conducted. As a result, as a non-woven fabric, a mold regeneration sheet using a non-woven fabric having a basis weight in the range of 70 to 600 g / m ² and a thickness in the range of 0.1 to 3.0 mm is used. When the surface (cavity surface) is cleaned, the nonwoven fabric effectively takes in the air in the cavity, and even when the cavity volume is large, the mold cleaning material spreads to every corner in the cavity. It has been found that the entire cavity can be cleaned and the present invention has been reached.

  That is, when the sheet for mold regeneration according to the present invention is sandwiched between an upper mold and a lower mold, a pattern with a raised shape (mold) composed of the unvulcanized rubber composition or the thermosetting resin composition is used. The top of the cleaning material) covers a part of the opening of the cavity, and the other part of the opening is not closed by the raised pattern (mold cleaning material) and remains open. Then, when the mold is clamped in that state, the mold cleaning material is filled into the cavity while gradually expanding the contact surface with the mold surface (cavity surface) of the mold from a part of the opening of the cavity. Along with this, air in the cavity is pushed out from the other part of the opening that is not blocked by the mold cleaning material. The extruded air is taken into the gaps between the fibers of the nonwoven fabric, thereby promoting air bleeding from the cavity. For this reason, even if the volume of the cavity is large, the air cannot be retained in the cavity, and the mold cleaning material is filled to every corner of the cavity. In this state, when the heat molding is performed, the mold cleaning material is vulcanized, and the mold surface (cavity surface) of the mold adheres to the vulcanized mold cleaning material. As a result, every corner of the cavity can be cleaned.

The sheet for mold regeneration of the present invention has a basis weight of 70 to 600 g / m ² and a thickness of 0.1 to 3.0 mm. The vulcanized rubber composition or the thermosetting resin composition forms a pattern with a predetermined raised shape having air venting voids, and the nonwoven fabric serving as the substrate is exposed from the air venting voids of the pattern. For this reason, when cleaning the mold using the mold regeneration sheet of the present invention, even if the cavity volume is large, the nonwoven fabric effectively takes in the air in the cavity and The air can be extracted. Thereby, the filling property of the mold cleaning material made of the unvulcanized rubber-based composition or the thermosetting resin-based composition is improved, and it becomes possible to clean every corner in the cavity.

  In addition, when the pattern is formed of a plurality of bands, lattices, or a plurality of spots, the shape and dimensions of the pattern and the air vent gap are easy to set, and the unvulcanized rubber composition or heat A mold cleaning material made of a curable resin composition can be easily set to a pattern suitable for filling into the cavity.

  In particular, the width and thickness of the strips and grids of vertical and horizontal stripes or spots are set within a range of 1 to 5 mm, and the gaps between adjacent bands and grids of vertical and horizontal stripes or spots are set within a range of 1 to 5 mm. In this case, the dimensions are appropriate for cleaning the transfer molding die used for resin-sealing the semiconductor element, and the transfer molding die can be properly cleaned.

  In particular, when the nonwoven fabric is a spunbonded nonwoven fabric, the tensile strength is relatively non-directional, and the stress applied during heat molding is easily absorbed and relaxed, so that sheet breakage is unlikely to occur during heat molding. In addition, since the sheet is not broken during the peeling (demolding) from the mold, the peeling (demolding) operation is simplified.

  Further, when the non-woven fabric is embossed, the surface of the non-woven fabric is roughened, so that the mold cleaning material comprising the unvulcanized rubber-based composition or the thermosetting resin-based composition is used. The anchor effect is further improved, and the adhesion between the nonwoven fabric and the mold cleaning material can be made stronger.

  When the nonwoven fabric is made of a thermoplastic resin having a melting point of 150 ° C. or higher, a nonwoven fabric having a melting point equal to or higher than the molding temperature at the time of cleaning can be used. The nonwoven fabric can be prevented from tearing when the mold regeneration sheet is removed after cleaning. For this reason, when the mold regeneration sheet is removed, the sheet can be removed in the form of one sheet, and the removal workability becomes simple.

  Next, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a first embodiment of a mold regeneration sheet of the present invention. The mold regeneration sheet of this embodiment has a non-woven fabric 1 as a base material and a plurality of protrusions on both surfaces by a mold cleaning material 2 made of an unvulcanized rubber-based composition or a thermosetting resin-based composition. A band-like pattern in which strips (bands) are arranged in parallel is formed. Each ridge which is a constituent element of this belt-like pattern is arranged in parallel with a gap between each other, and the gap between the adjacent ridges is an air bleeding gap at the time of mold cleaning. It has become. Further, in this embodiment, the mold cleaning material 2 is not formed between the adjacent ridges (the air evacuation gap), and the nonwoven fabric 1 serving as a base material is exposed. The air can be taken into the nonwoven fabric 1 during mold cleaning.

In more detail, the nonwoven fabric 1 are, within the scope basis weight of 70~600g / m ^2, in which the thickness is in the range of 0.1 to 3.0 mm. In such a nonwoven fabric 1, the gap between the fibers has a size appropriate for air intake. For this reason, when the mold surface (cavity surface) of the mold is cleaned, the nonwoven fabric 1 effectively takes in the air in the cavity, and as a result, the mold cleaning material 2 is moved to every corner in the cavity. Can be passed. Furthermore, the nonwoven fabric 1, by having the specific basis weight and (70~600g / m ²⁾ and thickness (0.1 to 3.0 mm), has become as having both flexibility and strength This is effective for cleaning the mold.

That is, when the basis weight of the nonwoven fabric 1 is less than 70 g / m ² and the thickness is less than 0.1 mm, the voids between the fibers of the nonwoven fabric 1 become small, and the nonwoven fabric 1 becomes air in the cavity when the mold is cleaned. As a result, the mold cleaning material 2 is not sufficiently filled in the cavity, and the cleaning property is deteriorated. In addition, the strength of the nonwoven fabric 1 also decreases, and when the mold regeneration sheet is removed after cleaning, the mold regeneration sheet may be torn off, and the demolding workability may be deteriorated. Conversely, if the basis weight of the nonwoven fabric 1 exceeds 600 g / m ² and the thickness exceeds 3.0 mm, the flexibility of the nonwoven fabric 1 is reduced, and the mold regeneration sheet becomes a mold when the mold is cleaned. As a result, the mold cleaning material 2 is not sufficiently filled in the cavity, and the cleaning performance is deteriorated. In addition, the function becomes useless volume and cost increases.

In addition, the nonwoven fabric 1 is usually formed with a rough surface, whereby the mold cleaning material (protrusion) 2 arranged side by side on the surface is embedded in the nonwoven fabric 1, Although anchoring property (anchor effect) is exhibited, in the present invention, the basis weight and thickness of the nonwoven fabric 1 are limited to the above specific ranges ( basis weight 70 to 600 g / m ² , thickness 0.1 to 3.0 mm). Thus, the rough surface of the nonwoven fabric 1 acts more effectively on the anchoring effect (anchor effect) of the mold cleaning material (projection) 2, and the nonwoven fabric 1 and the mold cleaning material (projection) 2 The adhesion is stronger. For this reason, when removing the mold regeneration sheet after cleaning, the nonwoven fabric 1 and the mold cleaning material (projection) 2 can be taken out in an integrated state, and the mold cleaning material 2 is used as the mold. It does not remain in the (cavity).

Furthermore, the nonwoven fabric 1 has the specific basis weight (70 to 600 g / m ² ) and the thickness (0.1 to 3.0 mm), so that the flow when the mold cleaning material 2 flows into the cavity. It can withstand the pressure (the tear strength of the nonwoven fabric 1 can be 8 N or more). Moreover, since the said nonwoven fabric 1 is not too hard, there is no possibility of damaging the guide pin etc. which were provided in the metal mold | die.

  And as a forming material of the said nonwoven fabric 1, the surface of the nonwoven fabric 1 can be made into an appropriate rough surface, the anchor effect of the mold cleaning material (projection) 2 is improved, and the mold cleaning material (projection) ) It is preferable to use long fibers from the viewpoint of making the adhesion strength with 2 stronger. Examples of the long fiber material include thermoplastic resins such as nylon (6-nylon, 6,6-nylon, etc.), polyester, and polypropylene. Of these, polyester is preferable from the viewpoint of heat resistance (cleaning). The molding temperature at this time is usually 150 to 180 ° C.).

  Further, the nonwoven fabric 1 is preferably a spunbonded nonwoven fabric from the viewpoint of mechanical strength, uniformity, and processability. Moreover, as the nonwoven fabric 1, the surface can be roughened, the anchor effect of the mold cleaning material 2 can be further improved, and the adhesion between the nonwoven fabric 1 and the mold cleaning material 2 can be made stronger. From the above, it is preferable that embossing is performed.

Thus, by non-woven fabric 1 has a thickness (0.1 to 3.0 mm) and the specific basis weight (70~600g / m ^2), but exhibits a beneficial effect for mold cleaning, this In order to make the effect more effective, the basis weight of the nonwoven fabric 1 is preferably in the range of 70 to 200 g / m ² and the thickness is preferably in the range of 0.2 to 2.0 mm.

  Next, the mold cleaning material 2 will be described in more detail. The size of the belt-like pattern by the juxtaposition of the protrusions is appropriately set depending on the size and arrangement of the mold cavities, and is not particularly limited. In particular, in the dimension of the degree to which the semiconductor element is resin-sealed (transfer molding), the width and thickness of each protrusion are set within the range of 1 to 5 mm, and the protrusions are adjacent (opposed) to each other. Is preferably set within a range of 1 to 5 mm. In addition, the shape of the cross section perpendicular to the longitudinal direction of each protrusion is shown as a trapezoidal shape in FIG. 1, but is not limited thereto, and is not limited thereto, but is a rectangle, a triangle, another polygon, a half A circle or the like may be used. Among these, even if the opening of the cavity is small, it is preferable that the top of each protrusion is formed in a non-flat shape from the viewpoint that it can be cleaned to every corner in the cavity (for example, The above-mentioned triangle, semicircle, etc.), more preferably, the non-flat shape is a convex portion within a radius of curvature of 0.2 to 3.0 mm.

  The color of the mold cleaning material 2 is not particularly limited, but is preferably a light color such as white or gray. The reason is that the dirt to be removed from the mold cavity is a dark color such as black, so after cleaning, it can be easily confirmed with the naked eye that the dirt has adhered to the mold regeneration sheet, This is because the cleaning status can be easily confirmed. In order to make the light color, a white pigment or the like is added to the unvulcanized rubber composition or the thermosetting resin composition for preparing the mold cleaning material 2.

  As described above, the mold cleaning material 2 is composed of an unvulcanized rubber-based composition or a thermosetting resin-based composition, and depends on the contents of cleaning shown in the following (A) and (B). The components mixed in the unvulcanized rubber composition are different. That is, in the above cleaning, (A) removing dirt on the mold surface (cavity surface) of the mold, and (B) removing dirt from the mold surface (cavity surface) of the mold, Imparting releasability to the mold surface (cavity surface).

  First, (A), that is, a first example of the mold cleaning material 2 for the purpose of removing dirt will be described. In this first example, an unvulcanized rubber fabric made of a mixture of unvulcanized rubber and glycol ethers represented by the following general formula (1) is used as a base material.

  The glycol ethers represented by the general formula (1) include ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, polyethylene glycol dimethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether. , Diethylene glycol monobutyl ether, diethylene glycol diethyl ether, diethylene glycol propyl ether, diethylene glycol dibutyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol mono Or the like can be mentioned Chirueteru.

Among the glycol ethers represented by the general formula (1), when n = 1 to ₂ , any one of R ₁ and R ₂ is hydrogen, the other is an alkyl group having 1 to 4 carbon atoms, , R ₁ and R ₂ are both alkyl groups, they are preferably alkyl groups having 1 to 4 carbon atoms. In addition, when n takes a value of 3 or more, compatibility with rubber is reduced, and when the carbon number of the alkyl group is 5 or more, the mold surface (cavity surface) of the mold There is a tendency that the permeability to dirt becomes worse.

  The above glycol ethers may be used as they are or mixed with water or alcohols such as methanol, ethanol and n-propanol, and organic solvents such as toluene and xylene. When mixing with an organic solvent, the amount of the organic solvent is usually 50 parts or less with respect to 100 parts by weight of glycol ethers (hereinafter abbreviated as “parts”), and most commonly 20 parts or less. To be done. Moreover, there is no problem even if a conventional release agent is used in an appropriate amount if necessary. When a release agent is used in combination, the amount used is 10 parts or less with respect to 100 parts of the total amount of unvulcanized rubber fabric and glycol ethers, most commonly 2 to 5 parts. To be done.

  Unvulcanized rubber includes natural rubber (NR), chloroprene rubber (CR), butadiene rubber (BR), nitrile rubber (NBR), ethylene propylene diene rubber (EPDM), ethylene propylene rubber (EPM), styrene butadiene rubber ( SBR), polyisoprene rubber (IR), butyl rubber (IIR), silicone rubber (Q), fluorine rubber (FKM), etc., alone or as a main component, and a vulcanizing agent is added and vulcanized as necessary. Those containing accelerators, reinforcing agents and the like are used. This unvulcanized rubber is vulcanized in the mold to become vulcanized rubber. EPDM, EPM, SBR, NBR, BR or a mixture thereof is preferable as the above-mentioned unvulcanized rubber. In addition, the said main component means the component which occupies the majority of the whole, and is the meaning including the case where the whole consists only of a main component.

The EPDM is a copolymer composed of ethylene, an α-olefin other than ethylene, and a cyclic or acyclic monomer having a non-conjugated double bond. More specifically, EPDM is a terpolymer composed of ethylene, an α-olefin other than ethylene (particularly propylene) and the polyene monomer listed below. Examples of the polyene monomer include dicyclopentadiene, 1,5-cycloocta Diene, 1,4-cyclooctadiene, 1,6-cyclododecadiene, 1,7-cyclododecadiene, 1,5,9-cyclododecatriene, 1,4-cycloheptadiene, 1,4-cyclohexadiene , Norbornadiene, methylene norbornene, ethylidene norbornene, 2-methylpentadiene-1,4,1,5-hexadiene, 1,6-heptadiene, methyl-tetrahydroindene, 1,4-hexadiene, and the like. The copolymerization ratio of each monomer is preferably a terpolymer in which ethylene is 30 to 80 mol%, polyene is 0.1 to 20 mol%, and the remainder is α-olefin. More preferably, ethylene is 30 to 60 mol%. And the thing with Mooney viscosity ML1 _{+ 4} (100 degreeC) of 20-70 is good.

As the SBR, those having a styrene content of 15 to 30 mol% and a Mooney viscosity ML _{1 + 4} (100 ° C.) of 20 to 80, preferably 35 to 60 are suitable.

As the NBR, it is preferable to use an NBR having an acrylonitrile content of 20 to 60 mol%, preferably 25 to 45 mol%, and a Mooney viscosity ML _{1 + 4} (100 ° C.) of 20 to 85, preferably 30 to 70. is there.

As the BR, 1,2 polybutadiene or 1,4 polybutadiene is used alone or in combination, and Mooney viscosity ML _{1 + 4} (100 ° C.) is 20 to 85, preferably 30 to 60.

  And the said glycol ether becomes unvulcanized rubber cloth by mixing with the said unvulcanized rubber. In this case, the glycol ether is usually blended in an amount of 10 to 60 parts with respect to 100 parts of the unvulcanized rubber. Preferred is about 15 to 25 parts. And it is preferable that the boiling point of the said glycol ethers is about 130-250 degreeC. That is, mold molding is usually performed at 150 to 185 ° C., and if the boiling point of the glycol ethers is less than 130 ° C., the evaporation during cleaning is significant, and therefore, the cleaning work environment may be deteriorated. On the contrary, if it exceeds 250 ° C., it becomes difficult to evaporate and remains in the vulcanized rubber, and the strength of the vulcanized rubber when it is taken out from the mold becomes weak and deformed. This is because it becomes difficult to sufficiently remove the dirt from the mold surface of the mold, and the cleaning workability tends to be reduced.

  The mold cleaning material 2 using the unvulcanized rubber fabric as a base material includes an inorganic reinforcing agent (such as silica, alumina, calcium carbonate, aluminum hydroxide, titanium oxide) as a reinforcing agent in the unvulcanized rubber. It is also possible to add a filler. In this case, the use amount of the reinforcing agent is preferably set to 10 to 50 parts with respect to 100 parts of the unvulcanized rubber. Further, as described above, a release agent can be blended. Examples of the release agent include stearic acid, zinc stearate, carnauba wax, montan wax, stearylethylenediamide and the like. It is possible to add 1 to 10 parts of these to 100 parts of unvulcanized rubber.

  Next, (A), that is, a second example of the mold cleaning material 2 for the purpose of removing dirt will be described. This second example is based on an unvulcanized rubber fabric made of a mixture of an unvulcanized rubber and at least one of imidazoles and imidazolines (imidazoles and / or imidazolines). In the second example, the difference from the first example will be mainly described.

  As the imidazoles, use of imidazoles represented by the following general formula (2) brings about good results. Representative examples of such imidazoles include 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 1-benzyl-2-methylimidazole, and the like, 2,4-diamino-6 [2 '-Methylimidazolyl (1)'] ethyl-s-triazine, 2,4-diamino-6 [2'-ethyl-4'-methylimidazolyl- (1) '] ethyl-s-triazine, and the like.

  As the imidazolines, use of imidazolines represented by the following general formula (3) brings about good results. Representative examples of such imidazolines include 2-methylimidazoline, 2-methyl-4-ethylimidazoline, 2-phenylimidazoline, 1-benzyl-2-methylimidazoline, 2-phenyl-4-methyl-5-hydroxy. Methyl imidazoline, 2,4-diamino-6 [2'methylimidazolyl- (1) '] ethyl-s-triazine, 2,4-diamino-6 [2'-methyl-4'-ethylimidazolyl- (1)' And ethyl-s-triazine, 1-cyanoethyl-2-methylimidazoline, 1-cyanoethyl-2-methyl-4-ethylimidazoline and the like.

  Next, (A), that is, a third example of the mold cleaning material 2 for the purpose of removing dirt will be described. In this third example, an unvulcanized rubber fabric made of a mixture of unvulcanized rubber and amino alcohols is used as a base material. In the third example, portions different from the first example will be mainly described.

  Use of the following amino alcohols as the amino alcohols brings about good results. That is, monoethanolamine, diethanolamine, triethanolamine, N-methylethanolamine, N, N-dimethylethanolamine, N, N-dibutylethanolamine, N, N-diethylethanolamine, N-methyl-N, N- Examples include diethanolamine, 2-amino-2-methylpropanol, 3-aminopropanol, and 2-aminopropanol.

  Next, (A), that is, a fourth example of the mold cleaning material 2 for the purpose of removing dirt will be described. In the fourth example, an uncured resin made of a thermosetting melamine resin mixture is used as a base material. In the fourth example, portions different from the first to third examples will be mainly described.

  As the thermosetting melamine resin mixture, it is generally preferable to use a melamine-formaldehyde resin. The melamine-formaldehyde resin is not particularly limited as long as it is a commercially available melamine resin cleaning material.

  Next, the above-mentioned (B), that is, the mold cleaning material 2 for the purpose of imparting releasability will be described. In this case, an unvulcanized rubber cloth made of a mixture of unvulcanized rubber and a release agent is used as a base material. Here, a different part from the said 1st example is mainly demonstrated.

  Examples of the release agent include long chain fatty acids such as stearic acid and behenic acid, metal salts of long chain fatty acids represented by zinc stearate and calcium stearate, carnauba wax, montan wax, and partially saponified esters of montanic acid. Specific examples include ester waxes, long-chain fatty acid amides represented by stearylethylenediamide, and paraffins represented by polyethylene wax.

  The mold cleaning material 2 can be obtained by mixing the unvulcanized rubber and the release agent by a known method, for example, using a calender roll or the like. It can also be obtained by a method such as kneading a release agent. In these cases, the release agent is usually blended in an amount of 1 to 50 parts per 100 parts of the unvulcanized rubber fabric. Preferred is 3 to 20 parts. And as said mold release agent, that whose melting | fusing point is 200 degrees C or less and whose boiling point is 200 degrees C or more is preferable. Furthermore, a thing with melting | fusing point of 50-150 degreeC is preferable. That is, mold molding is normally performed at 150 to 200 ° C. If the melting point of the release agent is higher than 200 ° C., the mold release agent does not exude to the mold surface and the boiling point is low. This is because if the temperature is lower than 200 ° C., the mold release agent evaporates even if it exudes to the mold surface, and the function tends to be lost.

  And the manufacturing method of the said sheet | seat for metal mold | die reproduction | regeneration is performed as follows using the said nonwoven fabric 1 and the metal mold | die cleaning material 2, for example. That is, first, the mold cleaning material 2 is kneaded with a continuous kneader or a batch kneader, and then disposed on both surfaces of the nonwoven fabric 1. Next, it is sandwiched and pressed between two molds in which concave portions corresponding to the protruding pattern (band pattern) of the mold cleaning material 2 are formed. And it winds up or cut | disconnects to an appropriate dimension. In this way, the mold regeneration sheet can be produced.

  A method of cleaning the mold surface (cavity surface) using such a mold regeneration sheet can be performed, for example, as follows. That is, first, as shown in FIG. 2, the mold regeneration sheet is sandwiched between the upper mold 11 and the lower mold 12. As a result, a part of the opening of the cavity 13 is blocked by the mold cleaning material 2, and the other part of the opening is not blocked by the mold cleaning material 2 and remains open. Then, the mold is clamped in this state. As a result, the mold cleaning material 2 of the mold regeneration sheet is pressed against the mold surfaces of the upper mold 11 and the lower mold 12 and filled into the cavity 13. At this time, air in the cavity 13 is pushed out from the other part of the opening of the cavity 13 that is not blocked by the mold cleaning material 2 as the mold cleaning material 2 is filled into the cavity 13. The extruded air is taken into the gaps between the fibers of the nonwoven fabric 1. As a result, air bleeding from the cavity 13 is promoted, and the mold cleaning material 2 is filled to every corner of the cavity 13. That is, the gap between the mold cleaning materials 2 adjacent to each other (facing each other) is an air vent gap, and the portion of the nonwoven fabric 1 exposed in the air vent gap is an air intake surface. Yes. Next, it heat-molds in this state. Thereby, the mold cleaning material 2 made of an unvulcanized rubber-based composition is heated and vulcanized to form a vulcanized rubber, and is molded into the shape of the cavity 13. At this time, the dirt in the cavity 13 is integrated with the vulcanized rubber 2a (see FIG. 3). Thereafter, as shown in FIG. 3, the upper mold 11 and the lower mold 12 are separated, and the mold regeneration sheet is removed. At this time, dirt on the mold surfaces (surfaces of the cavities 13) of the upper mold 11 and the lower mold 12 is transferred and integrated with the vulcanized rubber 2a and removed. In this way, cleaning is performed.

  In the above cleaning method, the case where the mold cleaning material 2 is made of an unvulcanized rubber-based composition has been described, but the mold cleaning material 2 made of a thermosetting resin-based composition is also used. It can be cleaned in the same way.

  Further, when the mold surfaces of the upper mold 11 and the lower mold 12 (surfaces of the cavities 13) are given release properties, the process is performed in the same manner. The contained release agent exudes, and release properties can be imparted to all corners of the cavity 13 (attachment of the release agent).

  FIG. 4 shows a second embodiment of the mold regeneration sheet of the present invention. In the mold regeneration sheet of this embodiment, the belt-shaped mold cleaning material (projection) 2 is formed on one side of a nonwoven fabric 1. Other than that, it is the same as the mold reproducing sheet of the first embodiment shown in FIG. 1, and the same reference numerals are given to the same parts.

  When using the sheet | seat for metal mold | die reproduction | regeneration of this 2nd Embodiment, as shown in FIG. 5, it folds so that the nonwoven fabric 1 may become inside, and uses it in the state which faced the nonwoven fabric 1 mutually. Thereby, there exists an effect | action and effect similar to the sheet | seat for metal mold | die reproduction | regeneration of the said 1st Embodiment.

  FIG. 6 shows a third embodiment of the mold regeneration sheet of the present invention. In the mold regeneration sheet of this embodiment, the protrusions in the mold regeneration sheet of the first embodiment shown in FIG. 1 are formed vertically and horizontally on both surfaces of the nonwoven fabric 1, thereby forming a lattice pattern. Is formed. Other than that, it is the same as the mold reproducing sheet of the first embodiment shown in FIG. 1, and the same reference numerals are given to the same parts. And the same operation and effect as the metallic mold reproduction sheet of the 1st embodiment of the above are produced.

  The protrusions in the third embodiment are shown to have the same height in FIG. 6 but are not limited to this, and are formed vertically and horizontally in order to improve air bleeding. You may make it make the height of the protrusion to do differ.

  FIG. 7 shows a fourth embodiment of the mold regeneration sheet of the present invention. In the mold regeneration sheet of this embodiment, the cleaning material 2 is formed in a spot-like pattern in which a plurality of truncated cones (spots) are scattered on both surfaces of a nonwoven fabric 1. Other than that, it is the same as the mold reproducing sheet of the first embodiment shown in FIG. 1, and the same reference numerals are given to the same parts. And the same operation and effect as the metallic mold reproduction sheet of the 1st embodiment of the above are produced.

  The shape of the mold cleaning material (spots) 2 in the fourth embodiment is a truncated cone in FIG. 7, but is not limited to this, and is not limited to a cone, a pyramid, a cylinder, It may be a prism, cylinder, square tube, or the like. In particular, from the viewpoint of enabling cleaning to every corner in the cavity 13 even if the opening of the cavity 13 is small, it is preferable that the top of each spot is formed in a non-flat shape (for example, The cone, the pyramid, etc.), more preferably, the non-flat shape is a convex portion within a radius of curvature of 0.2 to 3.0 mm.

  In the first to fourth embodiments, the mold cleaning material 2 is not formed between the adjacent mold cleaning materials (protrusions, spots) 2 (air venting gap). In that case, at least a part of the nonwoven fabric 1 needs to be exposed. This is because air is taken into the gaps between the fibers of the nonwoven fabric 1.

  Here, the dimension of the metal mold | die cleaning material 2 in this invention is demonstrated. The width of the projecting pattern is a value at the bottom of the projecting pattern. For example, when the projecting pattern is strip-shaped or grid-shaped, the width is a value perpendicular to the longitudinal direction of the projecting stripe, In this case, the bottom short diameter of the circle / ellipse and the rectangular bottom short side length are used, and in the other cases, the minimum diameter of the three-point inscribed circle of the bottom shape is used. The interval between the adjacent projecting patterns is a distance between the bottoms of the facing wall surfaces of the adjacent projecting patterns with reference to the bottom of the projecting pattern. In the case of an object having a rounded bottom (having a fret shape), the point where the extension line of the straight portion of the cross-section wall of the protruding pattern intersects the plane on which the protruding pattern is formed is the measurement point of the width and interval. It is the value. When a mold cleaning material 2 having a certain thickness is formed on a part of the surface of the nonwoven fabric 1 and a protruding pattern is formed thereon, the mold cleaning material 2 having a certain thickness is used instead of the surface of the nonwoven fabric 1. It is the width | variety and space | interval of the protrusion pattern in the surface of this. When the mold cleaning material 2 having a constant thickness is not formed, the width and interval of the protruding pattern on the surface of the nonwoven fabric 1 are set. These widths and intervals are set according to the dimensions of the mold forming the protruding pattern, and can be confirmed by measuring the produced mold reproduction sheet using a laser length measuring device or the like.

  Further, the thickness of the protruding pattern is such that the surface of the protruding pattern bottom surface (when the mold cleaning material 2 having a certain thickness is formed on the surface of the nonwoven fabric 1, the mold cleaning material 2 having a certain thickness is formed). , The length of the perpendicular to the surface of the non-woven fabric 1 when the mold cleaning material 2 having a constant thickness is not formed. This thickness is set by the dimension of the mold that forms the protruding pattern, and can be confirmed by measuring the manufactured sheet for sheet regeneration with a thickness measuring device such as a dial gauge.

  The radius of curvature of the top of the protruding pattern is set by the dimensions of the mold that forms the protruding pattern, and is confirmed by measuring the produced mold recycling sheet with a non-contact type three-dimensional measuring device. can do.

  Next, examples will be described together with comparative examples. However, the present invention is not limited to the examples.

[Nonwoven fabric]
Each nonwoven fabric having the basis weight and thickness shown in Tables 1 and 2 below was produced using polyester long fibers as a material.

[Die cleaning material: unvulcanized rubber composition]
100 parts of ethylene propylene rubber, 50 parts of silica powder, 5 parts of titanium oxide, 2 parts of organic peroxide [n-butyl-4,4-bis (t-butylperoxy) valerate], imidazole {2,4-diamino- A mold cleaning material was prepared by kneading 10 parts of 6- [2'-methylimidazolyl- (1 ')] ethyl-s-triazine} and 5 parts of montan wax with a kneader.

[Die cleaning material: Thermosetting resin composition]
A melamine resin cleaning material (commercially available) was prepared.

[Examples 1-8, Comparative Examples 1-3]
On both surfaces of the nonwoven fabric, the mold cleaning material was projected in the pattern (band shape, lattice shape, spot shape) and dimensions (width, thickness, gap) shown in Tables 1 and 2 below. In addition, the shape of the cross section perpendicular to the longitudinal direction of the belt-like and grid-like patterns was a rectangle, and the shape of each spot of the spot-like pattern was a cylinder.

[Filling rate / fillability]
The molds were cleaned using the mold regeneration sheets of Examples 1 to 8 and Comparative Examples 1 to 3 thus obtained. This mold is a pseudo mold for transfer molding used when resin-sealing a semiconductor element, and consists of an upper mold and a lower mold. Each mold surface of these upper mold and lower mold The (opposite surface) is a rectangle of 24 mm × 91 mm. Moreover, the shape of each cavity in the state clamped is a rectangular parallelepiped shape, and the dimension is 6 mm × 7 mm × 2 mm (height). Further, 16 cavities are formed, and 8 cavities are arranged in parallel in two rows. The interval between the two rows is 10 mm, and the interval between adjacent cavities in each row is 1 mm. The filling rate was evaluated for the filling rate of the cavity having the worst filling property among the 16 cavities. The filling rate was determined by the ratio between the bottom area of the cavity and the bottom area of the vulcanized rubber that was thermoformed into a cavity shape by cleaning. As a result, the case where the filling rate was 100% was evaluated as ◯, and the case where the filling rate was less than 100% was evaluated as ×, and the results were also shown in Tables 1 and 2 below. The cleaning conditions were as follows: the mold regeneration sheet had the same dimensions as the mold surface, the mold clamping gap was 0.5 mm, the molding temperature was 175 ° C., and the molding time was 5 minutes.

[Cleanability]
When the filling rate is 100%, it was possible to clean all the cavities, so it was evaluated as ◯. When the filling rate was less than 100%, 90% or more had a slightly inferior cavity cleaning, It evaluated with (triangle | delta) and it described together with following Table 1,2.

  From the results of Tables 1 and 2, it can be seen that the mold regeneration sheets of Examples 1 to 8 are more excellent in filling and cleaning than the mold regeneration sheets of Comparative Examples 1 to 3.

  In the evaluation of the filling rate / fillability, a mold having a cavity size of 6 mm × 7 mm × 3 mm (height) was used, but the cavity size was set to 4 mm × 5 mm × 2 mm (height). Even when the filling rate and filling property were similarly evaluated using a reduced mold, the mold recycling sheets of Examples 1 to 8 obtained results showing the same tendency as described above.

It is a perspective view which shows 1st Embodiment of the sheet | seat for metal mold | die reproduction | regeneration of this invention. It is explanatory drawing which shows the cleaning method using the said sheet | seat for metal mold | die reproduction | regeneration. It is explanatory drawing which shows the said cleaning method. It is a perspective view which shows 2nd Embodiment of the sheet | seat for metal mold | die reproduction | regeneration of this invention. It is explanatory drawing which shows the usage method of the said sheet | seat for metal mold | die reproduction | regeneration. It is a perspective view which shows 3rd Embodiment of the sheet | seat for metal mold | die reproduction | regeneration of this invention. It is a perspective view which shows 4th Embodiment of the sheet | seat for metal mold | die reproduction | regeneration of this invention.

Explanation of symbols

1 Nonwoven fabric 2 Mold cleaning material

Claims (7)

A mold regeneration sheet used for cleaning a mold surface of a mold, wherein a basis weight is in a range of 70 to 600 g / m ² and a thickness is in a range of 0.1 to 3.0 mm. A pattern of a predetermined raised shape having a void for air venting is formed on one side or both sides of a nonwoven fabric used as a material by a mold cleaning material made of an unvulcanized rubber-based composition or a thermosetting resin-based composition. The non-woven fabric used as the base material is exposed from the air-release air gap, and the exposed non-woven fabric portion is used as an air intake portion when the mold surface of the mold is cleaned using the space between the fibers of the non-woven fabric. A sheet for mold regeneration, which is formed.   2. The mold regeneration sheet according to claim 1, wherein a top portion of the pattern is formed in a non-flat shape.   The mold regeneration sheet according to claim 1 or 2, wherein the pattern is formed of a plurality of bands, lattices, or a plurality of spots.   The width and thickness of the strip, the vertical and horizontal stripes or spots of the lattice are set in the range of 1 to 5 mm, and the gap between the vertical and horizontal stripes or spots of the adjacent strip and lattice are set in the range of 1 to 5 mm. The mold regeneration sheet according to claim 3.   The sheet for mold regeneration according to any one of claims 1 to 4, wherein the nonwoven fabric is a spunbonded nonwoven fabric.   The mold regeneration sheet according to any one of claims 1 to 5, wherein the nonwoven fabric is embossed.   The mold regeneration sheet according to any one of claims 1 to 6, wherein the nonwoven fabric is made of a thermoplastic resin having a melting point of 150 ° C or higher.

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