JP7320825B2 - Resin bonded body and its bonding method - Google Patents

Description

The present invention provides a method of manufacturing various resin bonded bodies including those having a hollow structure inside the resin such as a channel chip, an optical waveguide element, an optical element, etc., by bonding a plurality of resin parts, and the results thereof. The present invention relates to a resin bonded body as a product. In particular, without using an adhesive containing different resin materials, a plurality of resin components containing thermoplastic resins are joined together to produce a relatively high-strength resin joint.

Conventionally, as a technique for joining a plurality of thermoplastic resin parts to each other, a method of bonding using an adhesive agent or adhesive tape, a heating tool, ultrasonic means, plasma treatment, etc. is used to bond at least the joint surface of the resin parts. A method of melting and joining the resin is adopted (Patent Document 1).

These joining methods join the joining surfaces of resin parts to each other to produce moldings with hollow structures such as channel chips, and complex moldings that cannot be molded in one step using injection molding. (Patent Document 2).
In the production of these bonded bodies, it is important to ensure high-precision bonding and bonding strength. In order to achieve high-precision bonding, it is required to reduce deformation of the resin component or the resin bonded body during the bonding process.

In recent years, a resin bonded body composed of a plurality of resin parts is formed by interposing a thin metal plate having unevenness and recesses on both surfaces between the resin parts to be joined. A technique for joining materials has been developed and a patent application has been filed (Patent Document 3). Improving the bonding strength between metal and resin parts by using the anchor effect of unevenness and recesses is being studied. Examples include anodized aluminum sheets with numerous nanoholes formed on the surface, and laser processing to create unevenness on the surface. A method of performing bonding by pouring a resin on the bonding surface of metal sheets having recesses has been reported (Patent Documents 4 and 5).

Japanese Patent Application Laid-Open No. 2006-172789 Japanese Patent Application Laid-Open No. 2009-095800 JP 2007-008077 A JP 2010-167475 A JP 2017-052127 A Japanese Patent No. 5317141

However, in the joining method using an adhesive or an adhesive tape, it is necessary to use a resin material different from that of the resin parts to be joined as the adhesive or the adhesive tape, and it is difficult to create a joined body made of a single resin. Can not. Furthermore, in the case of using a liquid adhesive, when joining resin parts having a hollow portion formed in the joint interface, the resin also flows into the inside of the hollow portion, thereby increasing the shape of the hollow portion. It is not possible to produce a resin bonded body having an integral structure while maintaining accuracy.

Thermal welding and ultrasonic bonding are methods suitable for bonding resin parts made of the same resin material.
However, in the heat welding method, if the resin parts have different thicknesses or have a complicated structure, at least a part of the resin parts melts and deforms to join them while maintaining precise shape accuracy. is not possible.
Further, the ultrasonic bonding method is a method of thermally welding the resin interface by exothermic melting due to the frictional heat of the bonding interface generated by the irradiation of ultrasonic waves. Such a heat welding method using ultrasonic waves has the advantage of being able to bond even complex resin parts without deformation of the resin parts. Therefore, in the case of the ultrasonic bonding method, especially when used for bonding resin bonded bodies in which a fine and precise hollow structure is formed at the bonding interface, such as a channel structure, the hollow structure Bonding near the ends of the body may be insufficient, and in such cases, it is difficult to precisely bond the bonded body.

In addition, in the above-described technique of forming unevenness or recesses on the joint interface and joining dissimilar materials by the anchor effect, anodization is limited to metal materials, and unevenness or recesses are formed on the joint interface of resin parts. is not possible. In addition, when laser processing is used to form irregularities and recesses on the bonding interface of one of the resin parts, the number of man-hours required for manufacturing resin parts, which are required to be produced at a lower cost than metal parts, is increased, and the price is reasonable. I have a problem that doesn't fit.

In this connection, if the mold for nanostructures previously developed by the present inventors (Patent Document 6) is used, it is possible to form a fine uneven surface of nanostructures on the surface of a resin component. However, according to the knowledge obtained by the inventors of the present invention, it is possible to bond resin parts together by using resin parts having concave and convex portions on the bonding interface and using only publicly known technical information. If this is done, the irregularities and recesses will be deformed during heat welding, and as a result, appropriate joint strength cannot be obtained, and the deformation of the resin joint body will be large. The shape corresponding to the function cannot be obtained.

The present invention aims to solve the problems in the prior art as described above, and provides a method for manufacturing a resin bonded body by joining a plurality of resin parts by heat welding, in which the resin parts are joined while maintaining precise shape accuracy. To provide a method capable of forming a resin bonded body consisting of only a single resin, and also capable of precisely forming, for example, a fine hollow structure inside the resin bonded body. is the subject.

The inventors of the present invention have obtained the following findings (A) to (F) as a result of intensive studies aimed at achieving the above objects.
(A) When joining a plurality of resin parts made of a thermoplastic resin material containing the same polymer by thermal welding, if resin parts having different glass transition temperatures and/or softening temperatures are used as the plurality of resin parts, Bonding between resin parts starts at the temperature of a resin material with a low glass transition temperature and/or softening temperature, and the bonding start temperature can be lowered. Also, the resin component with the higher glass transition temperature and/or softening temperature does not deform during bonding.
(B) A high glass transition temperature and/or a high softening temperature when a plurality of resin parts made of thermoplastic resin materials containing the same polymer and having different glass transition temperatures and/or softening temperatures are joined by heat welding. When forming an uneven structure with a size in the nano-value range on the surface of one resin part and bonding, only the resin material of the resin part with a low glass transition temperature and/or softening temperature is melted and deformed, and the glass transition temperature and/or Since the resin part with the higher softening temperature does not deform at the time of joining and the concave-convex structure remains, as a result, the melt-deformed resin material with the low glass transition temperature and/or the softening temperature is filled in the concave-convex structure. As a result, the bonding action of the resin occurs due to the anchor effect and fusion diffusion between the single resins, and the bonding can be performed firmly. In addition, since bonding starts from the temperature of the resin material with a low glass transition temperature and/or softening temperature, the resin parts with a high glass transition temperature and/or softening temperature are not deformed, thereby forming Deformation of the resin bonded body can be suppressed.
(C) The bonding of (B) above can be realized if the difference in glass transition temperature and/or softening temperature of the plurality of resin parts is 5° C. or more. The best glass transition temperature and/or softening temperature difference in this case is between 10°C and 25°C.
(D) In the bonding of (B) above, when a concave structure is formed at the bonding interface between a resin part having a high glass transition temperature and/or softening temperature and another resin part and the bonding is performed, the bonding interface is flat as a whole. Since it is a flat surface and hole-shaped concave structures are scattered in it, the flat surface first comes into contact with other resin parts at the time of bonding, and a uniform pressure is applied to the entire bonding interface. It relieves the pressure on the structure and prevents the structure from breaking. On the other hand, when the convex structures are scattered on a flat plane, the tips of the convex structures first come into contact with other resin parts during bonding, so that a large pressure is applied to the tips of the convex structures, and the convex structures are not formed. Since the tip is destroyed, the bonding strength due to the anchor effect is weak.
(E) In the bonding of (B) above, a resin material with a low glass transition temperature and/or softening temperature is deformed and melted, and filled in the concave-convex structure composed of a resin material containing the same polymer as the resin material. Therefore, a transparent resin bonded body with extremely little interface reflection can be realized.
(F) For the knowledge of (A) to (E) above, an experiment was conducted to thermally weld a plurality of resin parts made of thermoplastic resin materials that contain the same polymer and have different glass transition temperatures and/or softening temperatures. However, even if they do not contain the same polymer, if a plurality of resin parts are made of thermoplastic resin materials with different glass transition temperatures and/or softening temperatures, they can be separated from each other. By starting the bonding from the temperature of the resin material with a low glass transition temperature and / or softening temperature, only the resin material of the resin part with a low glass transition temperature and / or softening temperature is melted and deformed, and the glass transition temperature and / or The resin part with the higher softening temperature is not deformed at the time of joining, and the concave-convex structure remains, and as a result, the melt-deformed resin material with the low glass transition temperature and/or the softening temperature is filled in the concave-convex structure. As a result, at least the bonding action of the resin occurs due to the anchor effect between the resins, and the bonding can be performed firmly. It can be reasonably predicted that a resin part having a high temperature and/or a high softening temperature is not deformed, thereby suppressing deformation of a resin bonded body formed by bonding.

The present invention is based on the above findings by the present inventors, and the present application specifically provides the following inventions.
<1> k (here, k is a natural number from 1 to n) resin parts 1 made of polymeric thermoplastic resin material 1 and the thermoplastic resin material 1 having a glass transition temperature and/or a softening temperature of 5 ° C. or more and k or k+1 resin parts 2 made of thermoplastic polymer material 2 having a temperature lower than °C are alternately laminated, wherein the resin part 1 is the resin The surface to be bonded to the component 2 has a plurality of nano-recesses having a size in the nano-value range, and does not have projections protruding from the bonding surface to a height of 30 nm or more, and the resin bonded body, A resin bonded body, wherein 90% by volume or more of the recess volume of at least part of the nano-recesses is filled with the polymeric thermoplastic resin material 2 .
<2> The resin according to <1>, wherein the polymers contained in the polymeric thermoplastic resin material 1 and the polymeric thermoplastic resin material 2 share 50 mol% or more of their repeating units. zygote.
<3> The resin bonded body according to <2>, wherein the polymers have 60 to 100 mol % of repeating units in common.
<4> The resin bonded body according to <1>, wherein the polymeric thermoplastic resin materials 1 and/or 2 are selected from polystyrene-based resins and cycloolefin-based resins.
<5> The bonding surface of the resin component 1 has an average of 20 to 50 nano-recesses per 1 μm ² with a diameter of 100 to 2000 nm and a depth of 200 to 2000 nm, and has protrusions protruding to a height of 30 nm or more. The resin bonded body according to <1>.
<6> The resin bonded body according to <1>, which has a hollow structure having a size equal to or larger than a micron value inside the resin part 1 or on the bonding surface thereof with the resin part 2 .
<7> k (here, k is a natural number from 1 to n) resin parts 1 made of a polymer thermoplastic resin material 1, and the thermoplastic resin material 1 having a glass transition temperature and/or a softening temperature of 5 A method for manufacturing a resin bonded body in which k pieces or k+1 pieces of resin parts 2 made of a polymeric thermoplastic resin material 2 having a temperature lower than °C are alternately laminated,
(a) is made of thermoplastic polymer resin material 1, and the surface to be bonded to resin part 2 made of thermoplastic polymer material 2 by the following steps (b) and (c) is nano A glass transition temperature and/or a softening temperature lower than that of the thermoplastic resin material 1 by 5°C or more, and k resin parts 1 having a plurality of concave portions and no protrusions protruding from the bonding surface to a height of 30 nm or more. a preparation step of preparing k pieces or k+1 pieces of resin parts 2 made of polymeric thermoplastic resin material 2;
(b) a contacting step in which the joining surfaces of the resin component 1 and the resin component 2 are substantially brought into contact so that the resin component 1 and the resin component 2 are alternately laminated;
(c) The bonding surface between the resin component 1 and the resin component 2 is at a temperature equal to or higher than the glass transition temperature and/or softening temperature of the resin component 2 and lower than the glass transition temperature and/or softening temperature of the resin component 1. a heating and pressurizing step of pressurizing the resin part 1 and the resin part 2 so as to generate contact pressure while heating to
In the heating/pressurizing step, the thermoplastic resin material 2 fills at least 90% by volume of the recess volume of at least a part of the nano-recesses.
<8> The method according to <7>, wherein the polymers contained in the thermoplastic resin material 1 and the thermoplastic resin material 2 have 50 mol % or more of repeating units in common.
<9> The method according to <8>, wherein the polymers have 60 to 100 mol % of repeating units in common.
<10> The method according to <7>, wherein the polymeric thermoplastic resin materials 1 and/or 2 are selected from polystyrene-based resins and cycloolefin-based resins.
<11> The joint surface of the resin component 1 has an average of 20 to 50 nano-recesses per 1 μm ² with a diameter of 100 to 2000 nm and a depth of 200 to 2000 nm, and has protrusions protruding to a height of 30 nm or more. No, the method according to <7>.
<12> The inside of the resin part 1 or the bonding surface thereof with the resin part 2 has a hollow structure having a size of a micron number or more, and the resin bonded body after the step (c) has the same hollow structure. The method according to <7>, wherein the structure is maintained.

The present invention can further include the following embodiments.
<13> The method according to <7>, wherein n is a natural number of 2 or more and 10 or less.
<14> In the heating and pressurizing step, at least 50% by volume of the nano-recesses are filled with the thermoplastic resin material 2 so that the total volume of the recesses is 90% by volume or more, <7>- <13> The method for producing a resin bonded body according to any one of <13>.
<15> In <14>, in the heating and pressurizing step, the thermoplastic resin material 2 is filled so that at least 80% by volume of the nano-recesses is 90% by volume or more of the total volume of the recesses. A method for producing the resin bonded body described above.

According to the present invention, resin parts made of a plurality of polymeric thermoplastic resin materials having different glass transition temperatures and/or softening temperatures are laminated, and the glass transition temperature of the resin part having a low glass transition temperature and/or softening temperature is obtained. And / or higher than the softening temperature, by heat welding at a temperature lower than the glass transition temperature and / or the softening temperature of the resin parts having a high glass transition temperature and / or a high softening temperature, resin with a high glass transition temperature and / or a high softening temperature The low-temperature resin parts are melt-deformed and filled into the nano-recesses provided in the parts, so that precise and strong bonding between the resin parts can be realized.
According to the present invention, since thermal bonding can be performed at a temperature at which only one resin component melts and deforms, it is possible to bond resin components having different thicknesses, which could not be bonded by conventional thermal welding.
In addition, according to the present invention, thermal deformation due to thermal bonding is suppressed. Deformation of the channel structure and the like can be suppressed, precise bonding can be achieved, and the channel structure and the like can be maintained even in the resin bonded body after bonding.
In addition, the resin part having unevenness having a size in the nano range on its surface, which is used in the production method of the present invention, can be produced only by a molding process such as injection molding. According to the method, by simply combining a resin part having unevenness having a size in the nano range on the surface and a resin part having a lower glass transition temperature and/or a lower softening temperature than the resin part, conventional heat welding can be achieved. Since it can be produced without a large change in the method, it is possible to provide a resin bonded body that is low in cost, excellent in mass productivity, and improved in functionality.
Further, according to the present invention, resin parts can be directly joined together without intervening an adhesive, a metal anchor, or the like. By using a resin material having similar optical properties, such as one containing the same polymer, as the resin material, the concave-convex structure is completely filled with resin having the same optical properties, resulting in optical transparency. It is possible to produce a resin bonded body having a uniform structure.
Furthermore, by realizing bonding of the same resin, an integrally molded product with high waterproofness and airtightness can be produced.
As a result, integrally joined moldings can be provided not only for the medical, biotechnology, and drug discovery industries, but also for optical communication and optical member industries such as lenses.

Using a resin part 1 having a plurality of nano recesses in the nano numerical range on the joint surface and a resin part 2 having a glass transition temperature and/or a softening temperature lower than that of the resin part 1 by 5°C or more and having a flat joint surface, 1 is a schematic diagram showing a process of manufacturing a resin bonded body by contacting and heat-sealing the bonding surfaces of the resin component 1 and filling 90% by volume or more of the nano recesses of the resin component 1 with the resin of the resin component 2. FIG. A resin part 1 having a plurality of nano recesses in the nano numerical value range and large recesses in the micron numerical value or more on the bonding surface, and a polymer different from or the same polymer as the resin part 1, the glass transition temperature and / or softening temperature A resin part 2 with a temperature lower than 5°C and a flat joint surface is used, both joint surfaces are contacted and thermally welded, and 90% by volume or more of the nano recesses of the resin part 1 are filled with the resin of the resin part 2. FIG. 3 is a schematic diagram showing a process of manufacturing a resin bonded body having a hollow structure derived from the large concave portion of the resin component 1; (a) Pattern 1: A schematic diagram showing a process of manufacturing a resin bonded body by heat-welding two types of resin parts 1 and 2 that differ in glass transition temperature and/or softening temperature by 5°C or more. (b) Pattern 2: A plurality of resin parts 1 having a plurality of nano recesses in the nano numerical range on the bonding surface, and a glass transition temperature and/or softening temperature lower than that of the resin part 1 by 5 ° C. or more, and a flat bonding surface The resin parts 2 are interposed between a plurality of resin parts 1, and both joint surfaces are brought into contact and heat-sealed so that 90% by volume or more of the nano recesses of the plurality of resin parts 1 are covered with the resin parts 2. 1 is a schematic diagram showing a process of filling a plurality of resin parts 1 with a resin to bond them together to manufacture a resin bonded body. (c) Pattern 3: A plurality of resin parts 1 having a plurality of nano recesses in the nano numerical range on the joint surface, and a glass transition temperature and/or softening temperature lower than that of the resin part 1 by 5 ° C. or more, and a flat joint surface. Two or more resin parts 2 are used, and the two or more resin parts 2 are interposed between the plurality of resin parts 1 with a space therebetween, and both joint surfaces are brought into contact and heat-sealed to form the plurality of resin parts 1. 90% by volume or more of at least one nano-recessed part of the plurality of nano-recessed parts is filled with the resin of the resin component 2, the plurality of resin parts 1 are joined, and some of the nano-recessed parts remain inside. Schematic diagrams showing steps for manufacturing a resin bonded body. When a resin part made of COP resin 690R with a softening temperature of 138°C and a resin part made of COP resin 1020R with a glass transition temperature of 110°C are thermally welded together, the bonding surface of the resin part made of COP690R has nano recesses. Graph showing the effect of this on the bonding strength between resin parts at each bonding temperature (compared with the case where the bonding surface of resin parts made of COP690R does not have nano recesses). When two resin parts made of PS resin TF4000 with a softening temperature of 120°C are interposed between two resin parts made of PS resin TF4000 with a glass transition temperature of about 90°C and then thermally welded together, a resin part made of PS resin TF4000 Graph showing the effect of having nano-recesses on the joint surface on the bonding strength of resin parts at each bonding temperature (compared with the case where resin parts made of PS resin TF4000 do not have nano-recesses on the joint surface) .

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a resin bonded body and a method for manufacturing the same of the present invention will be described based on embodiments and examples. Redundant description will be omitted as appropriate. In addition, when a numerical range is expressed by describing "-" between two numerical values, these two numerical values are also included in the numerical range.

The present invention is a method of manufacturing a resin bonded body by bonding a plurality of resin parts by heat welding, in which the resin parts can be bonded while maintaining precise shape accuracy, so that the resin parts can be made of only a single resin. It is an object of the present invention to provide a method capable of forming a resin bonded body and precisely forming, for example, a fine hollow structure inside the resin bonded body.
In order to solve the above problems, in the present invention, two or more types of resin materials having different glass transition temperatures and softening temperatures are prepared, and injection molding, press molding, imprint molding, etc. are performed using these resin materials. By molding two or more molded articles (resin parts) having different glass transition temperatures and/or softening temperatures.
Here, one molded product (resin part) to be joined is molded using a mold with a nano-level convex structure formed on the surface, as shown in Fig. 1a). to form a nano-level recessed structure at the joint interface of the resin part. Here, the recessed structure is formed in a resin component that is molded using a resin material having a higher glass transition temperature and/or a higher softening temperature among the two or more types of resin components. On the other hand, the resin component having a lower glass transition temperature and/or softening temperature is not formed with an uneven structure at the bonding interface.
Next, as shown in FIG. 1d), the joint portions of the thus obtained resin parts having different glass transition temperatures and/or softening temperatures are put together and heat-sealed.
At this time, the heating temperature for thermal welding is lower than the glass transition temperature and/or the softening temperature of the resin material used for the resin part having the recessed structure, and is used for the resin part without the concave-convex structure. By setting the temperature to a temperature higher than the glass transition temperature and/or softening temperature of the resin material, thermal deformation of the resin part having the concave structure is reduced. The joint interface of the molded resin parts melts, and as shown in FIG. 1 e), by filling the melted resin into the concave structure, both resin parts can be thermally welded by the anchor effect. At this time, it is desirable to apply a pressure of about 0.1 Mpa to 0.4 Mpa or more so that contact pressure is generated between the two resin parts, for example, when the size of the resin parts is 40 mm×120 mm.
Thus, in the present invention, the difference in the glass transition temperature and the softening temperature of the resin material is used to appropriately control the temperature during heat melting, so that the resin parts that cause thermal deformation and the resin parts that do not. By filling the resin material that causes thermal deformation into the nano uneven structure of the resin part that does not cause thermal deformation by thermal melting of the resin part that causes thermal deformation, the resin parts are held together by the anchor effect. It is to be joined.

The method of performing the thermal welding is a method that can precisely apply heat to the points to be welded so that the welding can be performed at an appropriate temperature corresponding to the difference in the glass transition temperature and/or the softening temperature of the resin material. There is no particular limitation, but generally, it can be realized by using heat welding, ultrasonic welding, laser welding, or the like.
When laser welding is used, not only the difference in the softening temperature of the resin material, but also the heat generation difference due to the difference in the absorption rate of the resin material with respect to the oscillation wavelength of the laser light is used, and the resin is similarly filled in the recessed structure. and heat welding can be performed by the anchor effect.

The size of the nano concave structure effective for the present invention is preferably a structure having a diameter of about 2 μm to 100 nm and an aspect ratio of 0.5 or more. , a diameter of about 2 μm to 100 nm, a depth of about 2 μm to 200 nm, and an aspect ratio of 1 or more and 2 or less. In the present invention, it is desirable to have an average of 20 to 50 such concave structures per 1 μm ² of the joint surface.
In addition, the nano-concave structure has a normal distribution such as Gaussian distribution, and is composed of structures of various sizes, which enables stronger adhesion by exhibiting the adhesion due to the anchor effect. be. Specifically, when the diameter of the concave structure is uniform, sufficient adhesion cannot be exhibited unless the resin is filled up to a certain depth. , In the case where the resin filling depth is insufficient in the area where the height aspect ratio of the structure to the structure is about 0.2 to 0.5, the anchor effect is strongest in the area where the structure is small or the distance between the structures is short. can be demonstrated. On the other hand, when the resin filling depth is such that the structure is sufficiently filled with resin having a height aspect ratio of about 1 to 2 with respect to the structure, the area where the diameter and spacing of the structure of the uneven structure is large. to obtain the most effective anchor effect. This makes it possible to firmly bond the molded product.

The present invention utilizes the difference in glass transition temperature and softening temperature of resin materials to control the resin parts that generate thermal deformation and the resin parts that do not generate thermal deformation. If there is a cavity such as a channel, the channel can be joined without being thermally deformed when the channel is heat-sealed. Therefore, as shown in FIG. 2, a resin bonded body that maintains a hollow structure can be produced. As shown in FIG. 2, when the hollow structure is derived from a large recessed structure provided on the joint surface of a resin part that does not cause thermal deformation, the recessed structure is a nano-concave structure provided on the same joint surface. It should be well above the structure, on the order of microns or larger.
Further, when a resin part having no hollow structure is treated in the same manner, an integrally molded resin joined body having no hollow structure can be produced.

In the present invention, at least one of the glass transition temperature and the softening temperature may be 5° C. or higher, more preferably 10° C. or higher.
The thermoplastic resin used for realizing the present invention is not particularly limited, and specifically includes polystyrene (PS), acrylic resin (PMMA), polycarbonate (PC), cycloolefin polymer (COP), cyclic Olefin copolymer (COC), low density polyethylene (LDPE), high density polyethylene (HDPE), polypropylene (PP), polyethylene (PE), ABS resin, medium density polyethylene (MDPE), high linear low density polyethylene (LLDPE), Resins such as linear ultra-low density polyethylene (LVLDPE), polyamide resins such as nylon, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN) can be used. In addition, resins containing fillers such as CFRP fillers and glass fillers, cellulose nanofibers, inorganic materials such as metals and ceramics, and additive powders and particles made of synthetic materials thereof can also be used in thermoplastic resins.

One of the purposes of the present invention is to provide optical elements such as channel chips, optical waveguide elements and couplers for optical communication, lenses, polarizing plates, filters, etc., which have a hollow structure inside the resin and have transparency. An object of the present invention is to provide a thermoplastic resin-bonded molded product of a single resin.
Here, a single thermoplastic resin refers to a thermoplastic resin of the same material or the same resin. It conforms to the classification by the resin symbol specified in .
In order to solve the above problems, in the present invention, two or more types of resin materials containing the same polymer and having different glass transition temperatures and softening temperatures are prepared, and using these resin materials, as described above, Two or more types of resin parts having different glass transition temperatures and/or softening temperatures are produced, and these resin parts are thermally welded as described above to produce a resin bonded body.
The glass transition temperature and softening temperature of the resin material vary depending on the type of polymer contained in the resin material, the type of additive, the blending amount, and the like. Even resin materials containing the same polymer contain different additives depending on the grade of the resin material. temperature is different.
In the present invention, when a plurality of resin materials containing the same polymer are used as the resin material, the SP (Solubility Parameter) values of these resin materials are extremely close, and entanglement occurs due to the diffusion of molecules at the bonding interface. Therefore, there is an advantage that the strength of the welded portion can be increased as compared with the case of using a resin material containing different kinds of polymers.
By bonding resin materials of the same material, reflection and scattering at the bonding interface can be suppressed, so that a transparent resin bonded body can be realized and can be used for optical members and the like. Furthermore, by realizing the bonding of the same resin, an integrally molded product with high waterproofness and airtightness can be produced.

FIG. 3 shows some specific patterns of the resin bonded body of the present invention. In pattern 1, resin component 1 and resin component 2 are joined. In the pattern 2, the resin component 2 is sandwiched between two resin components 1, and the two resin components 1 are joined with the resin component 2 interposed therebetween. Furthermore, in the pattern 3, a pattern or the like is cut in the sandwiched resin component 2, thereby forming a bonded portion and a non-bonded portion (hollow portion) between the two resin components.

EXAMPLES The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

The details of the resin materials used for the resin bonded body evaluation samples according to the present invention, which were used to evaluate the bonding strength and the like of the resin bonded bodies in Examples 1 and 2 below, are as follows.
(1) Polystyrene resin material A test piece of 35 mm x 35 mm was molded by injection molding using a piece mold having a conical structure with an average diameter of Gaussian distribution centered at about 300 nm and a height of 350 nm. The reverse pattern of the surface structure of the piece mold is formed on the surface of the test piece, and conical holes with Gaussian distribution are formed. A test piece was prepared using a heat-resistant polystyrene resin (Toyo Styrene grade TF4000). The softening temperature of the polystyrene resin used is 120°C. Also, grade 679 manufactured by PS Japan Co., Ltd. was used as a polystyrene resin for deformation with a low softening temperature. The glass transition temperature is 96°C. In addition, when a film was used, Oishi Sangyo Co., Ltd. Styrophane grade: SPH was used as a polystyrene film for deformation. The glass transition temperature is approximately 90°C. As another film for deformation, an OSP film manufactured by Asahi Kasei Corporation was used. The glass transition temperature is approximately 100°C.

(2) Cycloolefin resin materials On the other hand, in the case of cycloolefin polymer resin (COP), similar to polystyrene resin, it has a Gaussian distribution average diameter centered at about 300 nm and a conical structure with a height of 350 nm. A 35 mm x 35 mm test piece was molded by injection molding using a piece mold. The reverse pattern of the surface structure of the piece mold is formed on the surface of the test piece, and conical holes with Gaussian distribution are formed. A test piece was prepared using a cycloolefin polymer resin (Grade 690R manufactured by Zeon Corporation). The softening temperature of the cycloolefin polymer resin used is 138°C. In addition, Nippon Zeon's grade 1020R was used as a deformable cycloolefin polymer resin having a low softening temperature. The glass transition temperature is 110°C.

<Example 1> Bonding strength test of sample form 1 (joining of resin part 1 having a nano recess on the joint surface and resin part 2 having a flat joint surface) Cycloolefin polymer resin (Japan A molded article having a nano uneven structure formed on the surface was used using Zeon's grade 690R cycloolefin (having 3 to 20 carbon atoms). In addition, as a resin molded article for surface modification, a molded article having an optical flat surface was used using Nippon Zeon's grade 1020R as a cycloolefin polymer resin. These two types of molded products were joined by heat welding. At this time, the heat welding temperature was set within a range from the softening temperature of the resin molded product for surface modification to the softening temperature of the heat-resistant resin molded product. Specifically, the bonding was performed at a heat welding temperature between 110°C and 138°C. In addition, the bonding strength evaluation after thermal welding was performed on the bonding strength in the vertical direction and the horizontal direction with respect to the concave structure. A tensile/thickness universal material testing machine "Tensilon series" was used as a bonding strength evaluation device. The bonding area for evaluation in the horizontal direction to the structure was 44 mm×20 mm, and the bonding area for evaluation in the vertical direction to the structure was 20 mm×20 mm. Also, the deformation of the molded product due to the heat welding temperature was evaluated based on the deformation of the edge of the molded product.

As a comparative example, heat-sealing was carried out using a molded article having an optical flat surface, using a cycloolefin polymer resin grade 690R manufactured by Nippon Zeon for both types of heat-resistant resin molded articles. In addition, cycloolefin polymer resin grade 690R made by Nippon Zeon was used as the heat-resistant resin molded product, and cycloolefin polymer resin made by Nippon Zeon grade 1020R was used as the resin molded product for surface modification. Thermal welding was performed using a flat molded product, and bonding evaluation was performed between the two.

Table 1 shows the results obtained for Sample Form 1 above.
Generally known cycloolefin polymer (hereinafter sometimes referred to as "COP") grade 690R part 1 and COP grade 690R part 2 are heat-welded to each other to produce a bonded molded product. If the bonding is not performed at a temperature higher than the softening temperature (138° C. in this case) of the resin parts 1 and 2, the resin will not be melted and softened, so the resin cannot be molecularly bonded at the interface between them. In this case, it was shown that the temperature of both joining surfaces must be 140°C or higher to join.
On the other hand, as explained in the present invention, even with COP, the softening temperature of the resin differs depending on the grade. At the softening temperature of 1020R softening temperature 110℃), since the resin with a low softening temperature is melted, it can be bonded at a lower temperature than before, and at a thermal bonding temperature above the softening temperature (or glass transition temperature) of the resin with a low softening temperature. I found that I could connect. Furthermore, when using a resin part with nano recesses molded on the surface of COP (COP 690R in this case), which has a high resin softening temperature, the anchor effect works and a stronger bond can be obtained, resulting in a bond that is 1.5 to 3 times faster. It was found that the strength can be improved (Fig. 4). In addition, by using the bonding method of the present invention, bonding can be performed at a temperature lower than the melting temperature of the resin-bonded product of COP (COP 690R in this case), which has a high resin softening temperature, so bonding can be performed with suppressed deformation of the resin-bonded product. It turned out.

<Example 2> Sample form 2 (joining of resin part 1 having a plurality of recesses on the joint surface-flat film joint piece for surface deformation (resin part 2)-resin part 1 having a plurality of recesses on the joint surface) Bonding Strength Test Table 2 shows the results of a bonding strength test performed on sample form 2 above.
When a generally known heat welding technique is used, as in Example 1, in the case of heat welding of polystyrene resin (PS TF4000) parts and polystyrene resin (PS TF4000) parts, the softening temperature of the resin (In this case, 120°C) or higher, the resin does not melt and soften, so molecular bonding of the resins facing each other at the bonding interface is not possible (usually, bonding requires heating at 125°C or higher, which is above the softening temperature. ).
On the other hand, as explained in this specification, even with polystyrene resin, the softening temperature of the resin differs depending on the grade, and in the case of thermal bonding utilizing this difference in softening temperature, a polystyrene resin film with a low softening temperature (this At the softening temperature of PS resin film (90℃-100℃), resin with a low softening temperature is melted, so it can be joined at a lower temperature than before. or glass transition temperature).
Furthermore, a polystyrene resin part 1 with a high resin softening temperature (in this case, for example, a resin part in which a plurality of nano recesses are formed on the bonding surface of PS TF4000) and a polystyrene resin part 2 with a low softening temperature are combined with the low softening temperature. When joining is performed at a joining temperature higher than or equal to the high softening temperature and lower than the high softening temperature, melt deformation occurs on the joining surface of the low softening temperature resin part, etc., and the low softening temperature resin is filled in the joining surface concave part of the other resin part 2. , stronger bonding strength can be obtained due to the anchor effect. In particular, when a plurality of nano-concavities are formed on the bonding surface of a high softening temperature resin part, bonding at a temperature equal to or higher than the low softening temperature of the low softening temperature resin part and less than the high softening temperature sharply increases the bonding strength. It can be improved (Figure 5).
Moreover, when the bonding method of the present invention is used, bonding can be performed at a temperature lower than the high softening temperature of polystyrene resin parts (PS TF4000 resin parts) with a high softening temperature, so that bonding can be performed while suppressing deformation of the resin bonded body.
Furthermore, when the same polystyrene resin is completely filled in a plurality of concave portions, the interfaces are integrated with the same resin, and the difference in refractive index between the resin parts 1 and 2 due to the difference in softening temperature is extremely small. It was found that a resin-bonded product with improved transmittance can be obtained by suppressing the occurrence of significant scattering and reflection.

INDUSTRIAL APPLICABILITY The present invention is useful for the production of parts that have complex structures and require transparency, such as flow path chips, optical waveguide elements and couplers for optical communication, lenses, polarizing plates, and optical elements such as filters. .

Claims (7)

k (here, k is a natural number from 1 to n) resin parts 1 made of polymeric thermoplastic resin material 1 and having a glass transition temperature and/or softening temperature lower than said thermoplastic resin material 1 by 5° C. or more A method for manufacturing a resin bonded body in which k or k+1 resin parts 2 made of thermoplastic polymeric resin material 2 are alternately laminated,
(a) made of thermoplastic polymeric resin material 1, and having a plurality of nano-concavities in the nano numerical range on the surface to be bonded to resin part 2 made of thermoplastic polymeric resin material 2 by the following steps (b) and (c); k resin parts 1 which do not have protrusions protruding from the joint surface to a height of 30 nm or more; a preparatory step of preparing k pieces or k+1 pieces of resin parts 2 made of resin material 2;
(b) a contacting step in which the joining surfaces of the resin component 1 and the resin component 2 are substantially brought into contact so that the resin component 1 and the resin component 2 are alternately laminated;
(c) The bonding surface between the resin component 1 and the resin component 2 is at a temperature equal to or higher than the glass transition temperature and/or softening temperature of the resin component 2 and lower than the glass transition temperature and/or softening temperature of the resin component 1. a heating and pressurizing step of pressurizing the resin part 1 and the resin part 2 so as to generate contact pressure while heating to
A method for manufacturing a resin bonded body, wherein at least a part of the nano-recessed portion is filled with the thermoplastic resin material 2 in the heating/pressurizing step. 2. The method according to claim 1 , wherein the polymers contained in said thermoplastic resin material 1 and said thermoplastic resin material 2 share 50 mol % or more of their repeating units. 3. The method of claim 2 , wherein the macromolecules have 60 to 100 mol % of their repeating units in common. 2. The method according to claim 1 , wherein said polymeric thermoplastic resin materials 1 and/or 2 are selected from polystyrene-based resins or cycloolefin-based resins. The joint surface of the resin component 1 has an average of 20 to 50 nano-concave portions per 1 μm ² with a diameter of 100 to 2000 nm and a depth of 200 to 2000 nm, and does not have a protrusion protruding to a height of 30 nm or more. Item 1. The method according to item 1 . 2. The method according to claim 1 , wherein the resin part 1 has a hollow structure with a micron number or more inside, and the structure is maintained even in the resin bonded body after the step (c). 2. The method according to claim 1 , wherein the resin component 1 and the resin component 2 have a concave structure with a micron number or more on the bonding surface thereof, and a hollow structure is produced in the resin bonded body after the step (c). Method.

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