JP2020124851A - Method for manufacturing resin molding, and sheet-like molding material - Google Patents

Abstract

To provide a resin molding that excels in shape stability when manufacturing a resin molding using a sheet-like molding material.SOLUTION: A method for manufacturing a resin molding 3 includes a step for curing a curable resin film 1 in a state in which a predetermined shape has been provided to the curable resin film 1 comprising a curable resin composition that contains an elastomer and a curable resin, and thereby forming the resin molding 3 being a cured body of the curable resin film 1.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for producing a resin molding and a sheet-shaped molding material.

A sheet-shaped molding material containing a resin material may be used to manufacture a sheet-shaped resin molded body provided with a predetermined shape (for example, Patent Document 1).

Japanese Unexamined Patent Application Publication No. 2018-152817

The shape of the resin molded body obtained by using the sheet-shaped molding material may change from the given shape due to the influence of heat or the like.

Therefore, an object of one aspect of the present invention is to obtain a resin molded product having excellent shape stability when a resin molded product is manufactured using a sheet-shaped molding material.

One aspect of the present invention is a state in which a predetermined shape is applied to a curable resin film made of a curable resin composition containing an elastomer and a curable resin, and the curable resin film is cured, whereby the curability is improved. The present invention relates to a method for producing a resin molded body including a step of forming a resin molded body which is a cured body of a resin film. Another aspect of the present invention relates to a sheet-shaped molding material that can be used in the method.

ADVANTAGE OF THE INVENTION According to this invention, when manufacturing a resin molded body using a sheet-shaped molding material, the shape change of a resin molded body resulting from heat etc. can be suppressed.

It is process drawing which shows one Embodiment of the method of manufacturing a resin molding. It is a photograph of a curable resin film before molding and a resin molded body after molding.

Hereinafter, some embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments.

FIG. 1 is a process diagram showing an embodiment of a method for producing a resin molded body. The method shown in FIG. 1 includes a step of preparing the curable resin film 1 ((a) of FIG. 1) and a predetermined curable resin film 1 by pressing the curable resin film 1 in the molds 11 and 12. In a state where the shape of the curable resin film 1 is given, thereby forming a resin molded body which is a cured body of the curable resin film 1 (FIG. 1B), and the resin molded body 3. Is taken out from the molds 11 and 12 ((c) of FIG. 1).

The curable resin film 1 of FIG. 1 is a single-layer film made of a curable resin composition containing an elastomer and a curable resin, provided that the curable resin film is composed of a plurality of curable resin layers having different configurations. It may be a laminated film constituted. The curable resin composition that constitutes the curable resin film 1 before being given a shape is usually in a substantially uncured state, but to the extent that the shape following ability for shaping is maintained. The curing may be partially advanced.

From the viewpoint of ensuring good moldability, the elastomer may be a thermoplastic elastomer. One example of the thermoplastic elastomer is a styrene-based thermoplastic elastomer. The styrene-based thermoplastic elastomer is, for example, a block copolymer containing a hard segment composed of a styrene block and a soft segment composed of a conjugated diene block (for example, a butadiene block). By using the styrene-based thermoplastic elastomer, the resin molded body 3 having excellent heat resistance can be obtained. The styrene-based thermoplastic elastomer may be a hydrogenated styrene-based thermoplastic elastomer obtained by hydrogenating a conjugated diene block.

The elastomer may have a crosslinkable group that forms a crosslinked structure by the reaction between the elastomers or the reaction between the elastomer and the thermosetting resin. By using an elastomer having a crosslinkable group, the heat resistance of the resin molded body 3 tends to be improved easily. Examples of the cross-linking group include an acid anhydride group, an amino group, a hydroxyl group, an epoxy group and a carboxyl group.

The elastomer may have a crosslinking group of at least one of an acid anhydride group and a carboxyl group. Examples of the elastomer having an acid anhydride group include an elastomer modified with maleic anhydride. Examples of commercially available styrene-based thermoplastic elastomers modified with maleic anhydride include "Tafprene 912" manufactured by Asahi Kasei Corporation, "FG1901" and "FG1924" manufactured by Kraton Polymer Japan Co., Ltd. There are "Tuftec M1911", "Tuftec M1913", and "Tuftec M1943".

Other examples of the elastomer include acrylic rubber, isoprene rubber, butyl rubber, styrene butadiene rubber, butadiene rubber, acrylonitrile butadiene rubber, silicone rubber, urethane rubber, chloroprene rubber, ethylene propylene rubber, fluororubber, sulfide rubber, epichlorohydrin rubber, and Chlorinated butyl rubber may be mentioned.

The weight average molecular weight of the elastomer may be 20,000 to 200,000, 30,000 to 150,000, or 50,000 to 125,000 from the viewpoint of film-forming properties of the curable resin composition. The weight average molecular weight (Mw) here means a standard polystyrene conversion value determined by gel permeation chromatography (GPC).

The curable resin is a compound having a reactive group for forming a crosslinked structure and curing the curable resin composition. The curable resin is selected from the group consisting of (meth)acrylic group, vinyl group, epoxy group, styryl group, amino group, isocyanurate group, ureido group, cyanate group, isocyanate group, mercapto group, hydroxyl group, and carboxyl group. It may be a compound having at least one reactive group. From the viewpoint of improving the heat resistance of the resin molded body 3, the curable resin may be an epoxy resin which is a compound having an epoxy group. A combination of an epoxy resin as a curable resin and an elastomer having an acid anhydride acid group or a carboxyl group can contribute to the heat resistance, low moisture permeability, and low tackiness of the resin molded body 3.

The epoxy resin may be a compound having two or more epoxy groups in order to obtain sufficient curability. Examples of the epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, naphthalene type epoxy resin, dicyclopentadiene type epoxy resin, and cresol novolac type epoxy resin. From the viewpoint of curability, low tackiness, and heat resistance, the epoxy resin is a phenol novolac type epoxy resin, a cresol novolac type epoxy resin, a naphthalene type epoxy resin, a dicyclopentadiene type epoxy resin, or two or more selected from these. May be included.

When the curable resin is an epoxy resin, the curable resin composition may further contain a curing agent for the epoxy resin. The curing agent may be a compound that reacts with the epoxy resin or a compound that accelerates the curing reaction of the epoxy resin (also referred to as “curing accelerator”). The curing agent includes, for example, at least one selected from the group consisting of imidazole compounds, aliphatic polyamines, polyaminoamides, polymercaptans, aromatic polyamines, acid anhydrides, carboxylic acids, phenol novolac resins, ester resins, and dicyandiamide. You can leave. The curable resin composition containing the epoxy resin and these curing agents can be cured by heating.

The curable resin may be a compound having a (meth)acrylic group. An example of the compound having a (meth)acrylic group is a (meth)acrylate compound. From the viewpoint of curability, the curable resin may contain a compound having two or more (meth)acrylic groups. When the curable resin is a compound having a (meth)acrylic group, the curable resin composition may further contain a thermal radical polymerization initiator, a photo radical polymerization initiator, or both of them.

The elastic modulus of the resin molded body 3 can be controlled based on the ratio of the curable resin and the elastomer. When the ratio of the curable resin is high, the elastic modulus of the resin molded body 3 tends to increase. For example, the content of the curable resin may be 10 parts by mass or more, 20 parts by mass or more, or 25 parts by mass or more, and 60 parts by mass or less, with respect to 100 parts by mass of the total amount of the elastomer and the curable resin. Alternatively, it may be 50 parts by mass or less. When the content of the curable resin is within these ranges, the resin molded body 3 having an appropriately high elastic modulus tends to be easily obtained while maintaining the good shapeability of the curable resin film 1. For example, the resin molded body 3 used as the diaphragm may be required to have an appropriately high tensile elastic modulus of about 3 to 30 MPa or about 5 to 20 MPa.

The total content of the elastomer and the curable resin in the curable resin film 1 or the curable resin composition that forms the curable resin film 1 or the curable resin composition is other than the filler and the organic solvent described below. It may be 60 to 100% by mass, 70 to 100% by mass, 80 to 100% by mass, or 90 to 100% by mass, based on the mass of the component.

The curable resin composition may further contain a filler dispersed in a resin matrix containing an elastomer and a thermosetting resin. The shape of the filler is not particularly limited, and may be substantially spherical, fibrous, or amorphous. The filler can be an inorganic filler, an organic filler, or a combination thereof. The filler may include at least one inorganic filler selected from the group consisting of silica, glass, alumina, titanium oxide, carbon black, mica, and boron nitride. The surface of the filler may be modified with a functional group. The functional group that can be introduced onto the surface of the filler includes, for example, an amino group.

The average particle size of the filler may be 10 to 500 nm. When the average particle diameter of the filler is within this range, more remarkable effects can be obtained in terms of reducing the coefficient of thermal expansion of the resin molded body 3 and suppressing the tackiness of the resin molded body 3 at high temperatures. From the same viewpoint, the average particle size of the filler may be 400 nm or less, 300 nm or less, 200 nm or less, 150 nm or less, or 80 nm or less. In the present specification, the average particle size of the filler means the average value of the particle sizes (average primary particle size) obtained by the laser diffraction/scattering method. The average particle size of the filler can be measured using, for example, a nanoparticle size distribution measuring device SALD-7500ano (manufactured by Shimadzu Corporation).

If the content of filler is large, the elastic modulus of the resin molded body 3 tends to increase. In order to obtain a resin molded body 3 having a moderately high elastic modulus while maintaining good shapeability of the curable resin film 1, the filler content is 100 parts by mass with respect to the total amount of the elastomer and the curable resin. , 10 parts by mass or more, 20 parts by mass or more, 30 parts by mass or more, 40 parts by mass or more, 50 parts by mass or more, 60 parts by mass or more, or 70 parts by mass or more, 100 parts by mass or less, or 90 parts by mass or more. It may be less than or equal to parts by mass.

The curable resin film 1 or the curable resin composition forming the curable resin film 1 may further contain other components, if necessary. Examples of other components include antioxidants, heat stabilizers, UV absorbers, hydrolysis inhibitors, anti-yellowing agents, visible light absorbers, colorants, plasticizers, flame retardants, and leveling agents.

The thickness of the curable resin film 1 is not particularly limited, but may be, for example, 5 to 1000 μm. In particular, when the resin molded body 3 is used as a diaphragm for a speaker, the thickness of the curable resin film 1 may be 50 to 200 μm.

The curable resin film 1 includes, for example, obtaining a resin varnish containing an elastomer, a curable resin, and other components optionally added, and an organic solvent, and forming the resin varnish on a release sheet. And removing the organic solvent from the resin varnish film on the release sheet. The exposed surface of the formed curable resin film 1 may be covered with a release sheet. Thereby, a sheet-shaped molding material having the curable resin film 1 and two release sheets respectively covering both surfaces of the curable resin film 1 is obtained. In the embodiment shown in FIG. 1, the curable resin film 1 from which the release sheet has been peeled is independently pressed in the molds 11 and 12.

Examples of the organic solvent for preparing the resin varnish include aromatic hydrocarbons such as toluene, xylene, mesitylene, cumene and p-cymene; cyclic ethers such as tetrahydrofuran and 1,4-dioxane; acetone, methyl ethyl ketone, methyl isobutyl. Ketones, cyclohexanone, ketones such as 4-hydroxy-4-methyl-2-pentanone; esters such as methyl acetate, ethyl acetate, butyl acetate, methyl lactate, ethyl lactate, γ-butyrolactone; carbonates such as ethylene carbonate and propylene carbonate Amides such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone. From the viewpoint of solubility and boiling point, toluene or N,N-dimethylacetamide may be used. These organic solvents can be used alone or in combination of two or more. The concentration of components other than the organic solvent in the resin varnish may be 20 to 80% by mass.

The release sheet may have a releasability such that it can be easily peeled off from the curable resin film 1 during use. The release sheet may be, for example, a polyester sheet such as polyethylene terephthalate (PET), polybutylene terephthalate, or polyethylene naphthalate. The thickness of the release sheet is not particularly limited, but may be 3 to 250 μm.

As shown in FIG. 1( b ), the curable resin film 1 is pressed in the molds 11 and 12 to give the curable resin film 1 a predetermined shape, Harden. Since the curable resin film 1 containing the elastomer and the curable resin has high elasticity, it can satisfactorily follow a shape including a greatly curved portion.

The curable resin film 1 can be cured by heating, irradiation with actinic rays, or a combination thereof. When the curable resin film 1 is cured by heating, the molding temperature and the molding time are adjusted within a range in which the curable resin reacts and a cured product is appropriately formed. For example, the molding temperature may be 80 to 250°C, or 100 to 200°C. The molding time may be 0.1 to 10 minutes. The molding pressure may be, for example, 0.1 to 10 MPa. The molding temperature is usually the temperature of at least one of the molds 11 and 12.

After molding and curing, as shown in FIG. 1C, the resin molded body 3 having a predetermined shape is taken out from the molds 11 and 12. The resin molded body 3 can maintain the imparted shape without being greatly damaged even when subjected to heat or the like. The resin molded body 3 having a moderately high elastic modulus and good heat resistance can be used as, for example, a diaphragm.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

1. Molding test 1-1. Resin varnish Toluene solution (concentration 25 mass%) of maleic anhydride-modified styrene/ethylene/butadiene thermoplastic elastomer (KRATON Corporation, trade name "FG1924GT") and dicyclopentadiene type epoxy resin (manufactured by DIC Corporation, product Name "EPICLON HP7200H") in toluene solution (concentration 25% by mass), and the mixture was stirred at 2000 rpm for 10 minutes using a rotation/revolution mixer. 1-Benzyl-2-methylimidazole (manufactured by Shikoku Kasei Co., Ltd., trade name "1B2MZ") was added to the mixture as a curing agent for the epoxy resin, and the mixture was stirred at 2000 rpm for 4 minutes to form a resin varnish. Obtained. The compounding ratio of each component in the resin varnish is as follows.
・Thermoplastic elastomer: 70 parts by mass ・Dicyclopentadiene type epoxy resin: 30 parts by mass ・1-Benzyl-2-methylimidazole: 3 parts by mass

1-2. Sheet-shaped molding material A release-treated polyethylene terephthalate (PET) film (manufactured by Teijin DuPont Films Ltd., trade name "Purex A31", thickness 25 µm) was prepared as a release sheet. The resin varnish was applied onto the release-treated surface of the release sheet using a knife coater (produced by Yasui Seiki Co., Ltd., trade name "SNC-350"). The coating film was dried by heating at 100° C. for 20 minutes in a dryer (manufactured by Futaba Kagaku Co., Ltd., trade name “MSO-80TPS”) to form a curable resin film having a thickness of 100 μm. A sheet-shaped molding material having a curable resin film in the B stage by pasting a release-treated PET film as a protective film on the formed curable resin film with the release-treated surface facing the curable resin layer side Got

1-3. Molding test The release sheet was peeled from the sheet-shaped molding material, and a wire having a thickness of 0.5 mm was placed on the exposed surface of the curable resin film. The release sheet peeled off was attached again from above the wire. The silicone rubber sheet was placed on the attached release sheet, and the whole was hot-pressed by a thermocompression-bonding press machine at a pressure of 0.2 MPa while heating to 140° C. for 3 minutes. By the hot pressing, the curable resin film was shaped and hardened, and a resin molded body having a shape including a recess in which the shape of the wire was transferred was formed. FIG. 2 is a photograph of a curable resin film before molding and a resin molded body after molding. (A) is a photograph of a curable resin film, and (b) is a photograph of a resin molded body. When the obtained resin molding was heated at 120° C. for 1 hour, the imparted shape was maintained.

2. Mechanical properties of cured product (resin molding) of curable resin film "1-1. Resin varnish" and "1-2. Sheet form" except that the compounding ratio of the thermoplastic elastomer and the dicyclopentadiene type epoxy resin was changed. In the same manner as the “molding material”, three types of sheet-shaped molding materials were produced. The curable resin film of each sheet-shaped molding material was heated in the order of 100° C. for 20 minutes and 180° C. for 60 minutes to obtain a cured product (resin molded product) on the film formed from the curable resin film. ..

Two release sheets were peeled from the obtained film-shaped cured body, and a strip-shaped test piece having a length of 40 mm and a width of 10 mm was cut out. The tensile test of this test piece was performed using an autograph (Shimadzu Corporation "EZ-S") to obtain a stress-strain curve. The elastic modulus and the elongation at room temperature were obtained from the obtained stress-strain curve. The tensile test was performed under the conditions of a chuck distance of 20 mm and a tensile speed of 50 mm/min. The tensile modulus was obtained from the slope of the stress-strain curve in the stress range of 0.5 to 1.0 N. The strain at the time when the test piece broke was recorded as the elongation. The measurement results are shown in Table 1. It was confirmed that when the ratio of the epoxy resin is high, a resin molded product having a higher elastic modulus can be obtained while maintaining a high elongation.

1... Curable resin film, 11, 12... Mold, 3... Resin molding.

Claims (11)

A curable resin film made of a curable resin composition containing an elastomer and a curable resin is given a predetermined shape, and the curable resin film is cured, whereby a cured product of the curable resin film is obtained. A method for producing a resin molded body, which comprises the step of forming a resin molded body. The method according to claim 1, wherein the predetermined shape is imparted to the curable resin film by pressing the curable resin film alone in a mold. The method according to claim 1 or 2, wherein the content of the curable resin is 25 to 50 parts by mass based on 100 parts by mass of the total amount of the elastomer and the curable resin. The method according to claim 1, wherein the curable resin composition further contains a filler. The method according to claim 1, wherein the curable resin comprises an epoxy resin. The method according to claim 1, wherein the resin molded body is a diaphragm. A sheet-shaped molding material comprising a curable resin film made of a curable resin composition containing an elastomer and a curable resin. The sheet-shaped molding material according to claim 7, further comprising two release sheets that respectively cover both surfaces of the curable resin film. The sheet-shaped molding material according to claim 7 or 8, wherein the content of the curable resin is 25 to 50 parts by mass based on 100 parts by mass of the total amount of the elastomer and the curable resin. The sheet-shaped molding material according to any one of claims 7 to 9, wherein the curable resin composition further contains a filler. The sheet-shaped molding material according to claim 7, wherein the curable resin contains an epoxy resin.