JP2005048130A - Composition for flexible resinous molded body having excellent adhesive performance at high temperatures and under shear, and flexible resinous molded body obtained therefrom - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composition which can give a flexible resinous molded body having together the flexibility and heat resistance and also having the excellent pressure-sensitive adhesion and under-shear adhesive performance at high temperatures. <P>SOLUTION: The composition for a flexible resinous molded body contains A: a solventless type of an acrylic-based copolymer containing a hydroxy group as a functional group of on the average from not less than 2.2 to not more than 2.7 per one molecule and having a number-average molecular weight of 8,000-30,000 and the fluidity at normal temperatures, B: a solventless type of an acrylic-based copolymer containing a hydroxy group as a functional group of on the average from not less than 1.3 to not more than 2.1 per one molecule and having a number-average molecular weight of 2,000-7,000 and the fluidity at normal temperatures, and C: a liquid isocyanate compound containing an isocyanate group as a functional group and having the fluidity at normal temperatures; and the flexible resinous molded body is obtained by curing the composition. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a composition for a soft resin molded body used for obtaining a flexible resin molded body having both flexibility and heat resistance, and a soft resin molded body obtained from the composition. The composition of the present invention can be used in various molding processes such as dip molding, casting and coating. In addition, the molded product of the present invention obtained from the present composition can be molded into various shapes in addition to a sheet shape, and can be used in a wide range of sites requiring heat resistance.

Conventionally, a thermoplastic resin (for example, soft polyvinyl chloride, polyethylene, polypropylene, etc.) is used as a material resin of a flexible material. However, these thermoplastic resins have low heat resistance, and are not suitable as material resins for materials that are used for a long time at high temperatures.
An example of the heat-resistant material having flexibility is vulcanized rubber. Vulcanized rubber is widely used in various applications as a heat resistant material. However, when vulcanized rubber is used as the heat resistant material, it is generally necessary to vulcanize the rubber molded in an unvulcanized state.

  When rubber is vulcanized with sulfur, in the molding process of the rubber molded body, the thermoplasticity of the rubber is maintained, and in the rubber vulcanization process, a three-dimensional cross-linked structure is constructed. The reaction must be controlled by a combination of a sulfur accelerator and a scorch inhibitor. Also, the rubber vulcanization process itself takes a long time at a high temperature. Furthermore, the obtained vulcanized rubber also has poor pressure-sensitive adhesive performance. For example, in order to use vulcanized rubber as an adhesive, the vulcanized rubber is added to a softener such as a plasticizer, an extender, and process oil. It is necessary to add a tackifier, and even in such a case, the heat-resistant shearing adhesion performance (the ability to withstand shearing stress and maintain adhesion at a high temperature) was not good.

  On the other hand, a certain kind of silicone rubber or gel exists as a two-component reaction liquid at room temperature, and is cured at room temperature by mixing the two liquids at a certain ratio (RTV silicone rubber). Are better. However, silicone rubber or gel is expensive. Silicone-based pressure-sensitive adhesives also exhibit good performance as adhesives, but when silicone is used for pressure-sensitive adhesives, it is difficult to select a release agent, and an expensive fluorine-based release agent Is often required.

Conventionally, acrylic copolymers have been used for various applications such as molded articles, adhesives, paints, fibers, and sealing agents.
Among the acrylic copolymers, the solventless acrylic copolymer is mainly obtained by a bulk polymerization method and does not contain a solvent.
The compounds used for obtaining the solvent-free acrylic copolymer, for example, compounds having double bonds such as acrylic acid, methacrylic acid, styrene and derivatives thereof are generally in the presence of a radical polymerization initiator. Polymerization is possible by a solution polymerization method [(solution method such as emulsion polymerization method (emulsion polymerization method)]), suspension polymerization method (suspension polymerization method, etc.) or bulk polymerization method (bulk method).

  Among the above polymerization methods, the solution polymerization method (emulsion polymerization method) and the suspension polymerization method polymerize the monomer in a liquid such as a reaction solvent or a dispersion medium, so that the polymerization conditions are easy to control, and therefore high efficiency. Thus, the intended homogeneous polymer can be produced relatively easily. When the polymerization is performed in a liquid, if the obtained polymer is solid, the polymer can be separated from the liquid relatively easily. However, if the polymer is a liquid, it is difficult to separate the polymer from the reaction solvent or dispersion medium. Therefore, even if the polymer itself remains liquid, the polymer and the reaction solvent or dispersion Not only complicated operations such as fractionation, filtration, and washing are required for separation from the medium, but even if such operations are performed, liquid components (solvent components) other than the polymer are polymerized. It is not easy to remove completely from.

On the other hand, since the bulk polymerization method (bulk method) does not use a liquid as a reaction medium, there is no problem such as separation of the liquid from the obtained polymer and impurities remaining in the obtained polymer. The advantage of being able to purify high-purity polymers is known, but with regard to (meth) acrylic polymers in particular, it is difficult to control the polymerization reaction and the resulting polymer structure and molecular weight are inferior. there were.
In recent years, however, these problems of bulk polymerization have been solved by the selection of a catalyst, the use of a monomer that also serves as an initiator, and the like, and it has become possible to obtain a polymer with high efficiency and a relatively uniform molecular weight distribution ( For example, see Patent Documents 1 to 6).

JP-T 59-6207 Japanese Patent Application Laid-Open No. 60-215007 Japanese Patent Laid-Open No. 10-17640 JP 2000-239308 A JP 2000-128911 A JP 2001-40037 A

  In order to provide a heat-resistant soft resin molded article that does not have a problem such as vulcanized rubber and is not as expensive as a silicone resin, the present inventors have provided a composition comprising an acrylic copolymer as a main material. We studied diligently. As a result, a composition containing, as a component, an acrylic copolymer that does not contain a solvent and has special physical properties, and a curing agent that does not contain a solvent (isocyanate compound) is cured, and preferably cured by heating. The present inventors have found that a soft resin molded article having good adhesion to materials, good heat resistance, and sufficient flexibility can be efficiently produced, thereby completing the present invention.

The present invention has been made to solve the problems of the prior art, and an object of the present invention is to provide a composition for obtaining a molded article having flexibility and excellent heat resistance. There is.
More specifically, an object of the present invention is a composition that is liquid at room temperature but can be easily cured by heating for a short time without requiring complicated reaction control as in the vulcanization process. Another object of the present invention is to provide a composition capable of providing a molded article having excellent long-term stability at a relatively high temperature.

That is, the composition for a flexible resin molded body of the present invention is
A: Solvent-free acrylic copolymer having a functional group containing 2.2 to 2.7 hydroxyl groups per molecule and having a number average molecular weight of 8000 to 30000 at room temperature,
B: Solvent-free acrylic copolymer containing 1.3 to 2.1 hydroxyl groups per molecule as a functional group and having a number average molecular weight of 2000 to 7000 and fluidity at room temperature, and C: A liquid isocyanate compound containing an isocyanate group as a functional group and having fluidity at room temperature is included.
The present invention also relates to a soft resin molded article obtained by curing the composition for a soft resin molded article of the present invention.

When the composition of the present invention is cured, it is a soft resin molded article having both good flexibility and good heat resistance, for example, the hardness at 25 ° C. is 50 or less in an ASKER-C hardness meter. It is possible to efficiently produce a flexible resin molded body having excellent flexibility and heat resistance.
In the shear holding test, this molded body has excellent heat-resistant shear adhesive strength that does not deviate from the initial position between the two aluminum plates even after 100 hours at 100 ° C. and even after 1000 hours. What has retention ability can be obtained.
Further, the composition of the present invention does not require complicated reaction control as in the conventional vulcanization process even when a molded body is produced, and can be easily obtained by heating a liquid composition at room temperature for a short time. It is possible to easily obtain the molded article of the present invention that can be cured at a relatively high temperature and can maintain excellent shear bonding performance over a long period of time at a relatively high temperature.

The acrylic copolymer as component A of the composition of the present invention is preferably in 2-ethylhexyl acrylate (2EHA), butyl acrylate (BA), methyl acrylate (MA) and ethyl acrylate (EA). The main component is one monomer component selected from
Furthermore, the acrylic copolymer as Component A preferably has a glass transition temperature (Tg, a value measured by DSC method) of −60 ° C. to −30 ° C. When the glass transition temperature of the acrylic copolymer as component A exceeds −30 ° C., the composition tends to be too hard and it becomes difficult to obtain a molded article having sufficient flexibility. Moreover, when the glass transition temperature of the acrylic copolymer as the component A is less than −60 ° C., the composition tends to be too soft and it is difficult to obtain a molded product having sufficient strength.

  The acrylic copolymer as component A contains an average of 2.2 or more and 2.7 or less hydroxyl groups per molecule as a functional group. In the acrylic copolymer as component A, specific methods for introducing a predetermined number of hydroxyl groups in one molecule include 2-ethylhexyl acrylate (2EHA), butyl acrylate (BA), and methyl acrylate (MA). A method for copolymerizing acrylic monomers such as ethyl acrylate (EA) and acrylic monomers containing primary hydroxyl groups such as hydroxyethyl methacrylate (HEMA), hydroxyethyl acrylate (HEA), hydroxypropyl acrylate (HPA), etc. In addition, a method of introducing a hydroxyl group at one end (for example, a method of polymerizing an acrylic monomer in the presence of a metallocene compound and a thiol having at least one hydroxyl group in the molecule), etc., more reliably in one molecule. A method of introducing one hydroxyl group may also be used.

When the average number of hydroxyl groups per molecule of the acrylic copolymer as component A is less than 2.2, the molded product obtained from the composition exhibits sufficient flexibility and tackiness, but is heat resistant. This tends to decrease the decoction strength and is liable to cause shear cohesive failure. Conversely, when the average number of hydroxyl groups per molecule of the acrylic copolymer as component A is more than 2.7, the heat-resistant shearing adhesive force is sufficiently expressed in the molded product, but the hardness increases. It lacks flexibility.
The acrylic copolymer as component A needs to exhibit fluidity at normal temperature (preferably 1013 hPa, 25 ° C.) and preferably has a viscosity of 40 Pa · s or less. When the viscosity of the acrylic copolymer as the component A is higher than 40 Pa · s, the fluidity is lowered, and the workability at the time of producing the molded body (for example, mixing with the component B or the component C) tends to be inferior. There is.
The acrylic copolymer as component A must further have a form that does not contain a solvent (solvent-free type) so that voids are not generated during the production of the molded article.

  The viscosity of the component A is a value measured with a Brookfield BH rotational viscometer. The flow characteristics of the acrylic copolymer as component A are such that when it exhibits thixotropic flow, the viscosity is preferably 40 Pa · s or less with the shear rate increased, and when it exhibits dilatant flow, the shear rate is Even at extremely low shear, the viscosity is preferably 40 Pa · s or less.

The molecular weight of the acrylic copolymer as Component A is 8000-30000, preferably 9000-20000, in terms of polystyrene in terms of polystyrene as measured by gel permeation chromatography (GPC).
When the molecular weight of the acrylic copolymer as the component A is less than 8000, the molded product obtained by curing the composition tends to be hard (hardness is increased). When the molecular weight of the acrylic copolymer exceeds 30000, the viscosity of the liquid component A before curing becomes too high, and workability at the time of mixing with other components deteriorates. If the viscosity of component A becomes too high, voids are likely to be formed and homogeneous mixing with component C (curing agent) becomes difficult. Therefore, the adhesive state when this composition is used as an adhesive is difficult. It is not preferable in terms of reliability.

The acrylic copolymer as component B of the composition of the present invention is preferably in 2-ethylhexyl acrylate (2EHA), butyl acrylate (BA), methyl acrylate (MA) and ethyl acrylate (EA). The main component is one monomer component selected from
Furthermore, the acrylic copolymer as Component B preferably has a glass transition temperature (Tg, a value measured by DSC method) of −60 ° C. to −30 ° C. When the glass transition temperature of the acrylic copolymer as Component B exceeds −20 ° C., the composition tends to be too hard and it is difficult to obtain a molded product having sufficient flexibility. Moreover, when the glass transition temperature of the acrylic copolymer as the component B is less than −60 ° C., the composition tends to be too soft and it is difficult to obtain a molded product having sufficient strength.

  The acrylic copolymer as component B contains an average of 1.3 to 2.1 hydroxyl groups per molecule as functional groups. In the acrylic copolymer as Component B, specific methods for introducing a predetermined number of hydroxyl groups in one molecule include 2-ethylhexyl acrylate (2EHA), butyl acrylate (BA), and methyl acrylate (MA). A method for copolymerizing acrylic monomers such as ethyl acrylate (EA) and acrylic monomers containing primary hydroxyl groups such as hydroxyethyl methacrylate (HEMA), hydroxyethyl acrylate (HEA), hydroxypropyl acrylate (HPA), etc. In addition, a method of introducing a hydroxyl group at one end (for example, a method of polymerizing an acrylic monomer in the presence of a metallocene compound and a thiol having at least one hydroxyl group in the molecule), etc., more reliably in one molecule. A method of introducing one hydroxyl group may be used.

  When the average number of functional groups per molecule of the acrylic copolymer as Component B is less than 1.3, the molded product obtained from the composition exhibits sufficient flexibility and tackiness, but is heat resistant. The shear adhesive force tends to decrease, and shear cohesive failure tends to occur, which is not preferable. On the other hand, if the average number of functional groups per molecule of the acrylic copolymer as component B is more than 2.1, the heat-resistant shearing adhesive force is sufficiently expressed in the molded body, but the hardness increases. It lacks flexibility.

Further, the acrylic copolymer as Component B needs to exhibit fluidity at normal temperature (preferably 1013 hPa, 25 ° C.), and preferably has a viscosity of 30 Pa · s or less. When the viscosity of the acrylic copolymer as the component B is higher than 30 Pa · s, the fluidity is lowered, and the workability at the time of production of the molded body (for example, at the time of mixing with the component A and the component C) tends to be poor. There is.
The acrylic copolymer as component B must further have a form that does not contain a solvent (solvent-free type) so that voids are not generated during the production of the molded article.

  The viscosity of the component B is a value measured with a Brookfield BH rotational viscometer. When the flow characteristics of the acrylic copolymer as component B is thixotropic, the viscosity is preferably 30 Pa · s or less when the shear rate is increased, and when the dilatant flow is exhibited, the shear rate is Even at extremely low shear, the viscosity is preferably 30 Pa · s or less.

The molecular weight of the acrylic copolymer as Component B is 2000 to 7000, preferably 3000 to 6000, in terms of number average molecular weight in terms of polystyrene as measured by gel permeation chromatography (GPC).
Component B has a smaller average molecular weight than Component A, and has a smaller number of average functional groups per molecule, so it has better fluidity than Component A. Therefore, when mixed with Component A, the entire mixed system There is an advantage that the viscosity of can be reduced. Furthermore, since the average number of functional groups contained per molecule in Component B is moderately low, moderate tackiness can be exhibited, and the pressure-sensitive adhesive performance of the composition can be improved.

  When the average molecular weight of the acrylic copolymer as the component B is less than 2000, the heat-resistant shear adhesive strength of the composition tends to be reduced due to the generation of an extremely low molecular weight component. When the average molecular weight of the polymer exceeds 7000, the viscosity of the liquid component B before curing becomes too high, and workability at the time of mixing with the component A is not preferable.

  Although the exact reason is unknown, as a result of intensive studies in the course leading to the present invention, as an acrylic copolymer, a polymer having an intermediate property between component A and component B (average molecular weight is 10,000) Rather than using a polymer having an average number of hydroxyl groups contained in one molecule of about 2.1 to 2.3), component A and component which are two types of acrylic copolymers having different properties It was found that it was more preferable to prepare B separately and mix these two kinds of components at a suitable ratio in terms of the balance between flexibility and heat resistance in the obtained molded article.

In the composition for a soft resin molded article of the present invention, the hydroxyl group (—OH) of the solventless acrylic copolymer as component A and the hydroxyl group (—OH) of the solventless acrylic copolymer as component B The liquid isocyanate compound of component C is used as a curing agent that reacts to give a cured product.
The liquid isocyanate compound of component C is liquid at normal temperature (preferably 1013 hPa, 25 ° C.), and the weight loss after heating at 100 ° C. for 10 minutes under 1013 hPa is 3% or less with respect to the weight before heating. A substantially solvent-free one is desirable.
The weight loss value after heating is based on the weight change before and after heating when 5 g of a sample was heated at 100 ° C. for 10 minutes under normal pressure (1013 hPa) using an EG53 halogen moisture meter manufactured by METTLER TOLEDO. It is a calculated value.

The liquid isocyanate compound of component C is at least
C1: carbodiimide-modified methylene diphenyl diisocyanate,
A compound containing C2: methylene diphenyl diisocyanate and C3: a prepolymer of methylene diphenyl diisocyanate and a diol, wherein the proportion of component C1 is 10 to 97% by mass based on the total mass of component C is preferred.

で表わされるメチレンジイソシアネート（ＭＤＩ）を変性することにより、次式（２）：

で表わされる３量体（ウレトンイミン）や、次式（３）：

で表わされる５量体（ウレトンイミン）、及び６量体以上の多量体を生成せしめた、常温常圧で液状を呈するものである。 The carbodiimide-modified methylene diphenyl diisocyanate as component C1 is represented by the following formula (1):

By modifying methylene diisocyanate (MDI) represented by the following formula (2):

A trimer represented by the formula (uretonimine), and the following formula (3):

It exhibits a liquid state at normal temperature and pressure, in which a pentamer (uretonimine) represented by the formula (1) and a hexamer or higher multimer are produced.

  The prepolymer of methylene diphenyl diisocyanate and diol as component C3 is a methylene diphenyl diisocyanate of formula (1) and an adipic acid type diol such as ethylene adipate (EA), butylene adipate (BA), propylene adipate (PA). ) And the like are particularly preferably used. The prepolymer used here is not particularly limited, but a prepolymer having an NCO content of about 5 to 10% by mass is preferable.

  The mixing ratio of component C1 to component C3 may be appropriately selected. However, if the ratio of C1 to the total amount of component C1 to component C3 is small (less than 30% by mass), the composition is liquid at room temperature and normal pressure. It is difficult to maintain the properties, which may cause crystallization during storage, which is not desirable. Further, if the ratio of C3 to the total amount of components C1 to C3 is very small (less than 3% by mass), the molded product obtained from the present composition is weak and brittle, which is not preferable.

  In addition to component C1 to component C3 methylenediphenyl diisocyanate-based isocyanate compound, component C is liquid at room temperature and normal pressure, such as tolylene diisocyanate (TDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), etc. It is also possible to mix these isocyanate compounds at appropriate ratios, and also, isocyanate compounds such as tolylene diisocyanate (TDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI) and short chain diols There is no problem in using the prepolymer.

  Moreover, as a liquid isocyanate compound of component C, in addition to the bifunctional isocyanate compound (isocyanate compound which has two isocyanate groups in a molecule | numerator) like the said component C1-component C3, it is trifunctional or more than isocyanate. It is preferable to further add a compound (an isocyanate compound having at least three isocyanate groups in the molecule; component D). For example, as a trifunctional isocyanate (component D), a buret body of isocyanate may be mentioned. The addition ratio of component D is appropriately selected.

  In the present composition, Component A or Component B is a solventless acrylic copolymer obtained from a monomer mixture mainly composed of monomers having a boiling point of 200 ° C. or higher, and is in the structural unit of Component A or Component B. May contain 80% by mass or more of the monomer. The monomer mixture may be appropriately selected. For example, a commercially available product may be used.

An inorganic or organic filler (or filler) can be added to the composition of the present invention as necessary. However, it is not preferable to use a filler (or filler) that inhibits the reaction between the components of the composition or generates a decomposition product during heat curing and use of the composition. Specifically, a filler of metal carbonate or metal hydroxide having a decomposition temperature of 250 ° C. or higher is particularly preferably used.
In order to impart a specific function to the composition, for example, in order to improve flame retardancy, a filler such as aluminum hydroxide can be added.
Moreover, there is no problem in blending calcium carbonate or the like as a bulking agent.

  In the measurement of the decomposition temperature, only the filler (or filler) is heated by TGA (Thermo Gravimetric Analyzer) in an air atmosphere from room temperature to 600 ° C. at a heating rate of 10 ° C./min. Was used to measure the temperature at which weight loss occurred and to determine the decomposition temperature.

  The size and shape of the filler (or filler) that can be used in the composition of the present invention are not particularly limited, but those having a particle diameter of 0.5 to 30 μm and a similar spherical shape are particularly preferably used. It is done. When the particle size of the filler is smaller than 0.5 μm, the viscosity of the liquid resin component becomes too high when added to the liquid resin component of the present composition. Conversely, when the particle size is larger than 30 μm, the liquid resin component In addition, when the composition is cured to form a main molded body, the filler is difficult to uniformly disperse in the main molded body.

These fillers are not preferred to contain water of crystallization, and the filler having water absorption is preferably dried by heating before mixing.
The fillers can also be used in combination with the same or different composition and different particle sizes. In particular, when it is necessary to increase the amount of the filler added, it is preferable to combine several kinds of fillers having different particle diameters because the viscosity of the composition can be lowered.

  The composition of the present invention that can obtain a molded article by mixing and stirring component A and component B, which are acrylic copolymers containing a hydroxyl group, and component C containing an isocyanate group, By including the catalyst component, it becomes possible to suitably control the reactivity. The catalyst component is not particularly limited, and those generally used for the reaction between a hydroxyl group and an isocyanate group can be used. For example, a quaternary ammonium salt, a tertiary amine, an organic tin compound, an organic bismuth compound, or the like is preferably used as the catalyst component.

Specific examples of the quaternary ammonium salt include triethylbenzylammonium chloride (TEBAC), tetrabutylammonium chloride (TBAC), and tetramethylammonium chloride (TMAC).
Specific examples of the tertiary amine include triethylenediamine (TEDA) and benzyldimethylamine.
Examples of the organotin compound include stannous octoate, dibutyltin dilaurate (DBTDL), dibutyltin dimaleate (DBTDM), and the like.

  The blending amount of the catalyst component to be added is preferably 0.005 to 1 part by mass, and 0.01 to 0.5 part by mass with respect to 100 parts by mass of the total of component A and component B (component A + component B). More preferred.

  Furthermore, depending on the performance required for the soft resin molding of the present invention obtained from the composition of the present invention, it is necessary for the main agent (component A and component B) and the curing agent (component C) of the present composition. Accordingly, various additives such as a colorant such as a pigment, an antioxidant, and a weathering stabilizer can be appropriately added.

  As a method of mixing the catalyst or additive with the present composition, a method of mixing the component A and the component B in advance and then mixing the component C is preferable.

As a method of blending Component A and Component B at an appropriate ratio, a method of weighing each of them and mixing and stirring can be mentioned. The mixing and stirring method at this time is not particularly limited, and may be selected according to the composition of component A or component B, the viscosity, the type of filler (or filler), and the blending amount. It is possible to apply a method using a stirrer such as a mixer or a homomixer. When a filler is mixed in advance with each component of the present composition, the same method as described above can be used.
In addition, for the purpose of removing a lump of undispersed filler or the like, a mixture that has been mixed and stirred (for example, a mixture of component A and component B) has no problem even if it is filtered as necessary. .
In the mixing and stirring, defoaming can be performed after stirring with the stirrer, and mixing and stirring can be performed with a static mixer. In the mixing and stirring operation, it is preferable that bubbles generated in the liquid are degassed under reduced pressure.

  As a typical molding process of the flexible resin molded article of the present invention, the main agent (component A and component B; solvent-free acrylic co-polymer) mixed preferably immediately in the presence of a catalyst component and immediately before the molding process. Polymer) and a curing agent (component C; liquid isocyanate compound) may be reaction-cured in a paste-like mixture obtained by mixing and stirring, or in a combination of the main agent and the curing agent at room temperature. When progress is slow, you may carry out reaction hardening by heating the paste-like mixture obtained by mixing and stirring the main ingredient and the hardening | curing agent which were mixed uniformly.

Although the heating temperature at the time of obtaining the soft resin molding of this invention changes with the property of each component resin type | system | group, the kind and addition amount of a catalyst, it is good to set it to about 90 to 150 degreeC, for example. In addition, the present soft resin molded article may be a molded article having a three-dimensional shape by pouring a paste-like mixture obtained by mixing and stirring the main agent and the curing agent into a mold, and It is good also as a sheet-like molded object by coating on the film (separator film), paper (release paper) etc. which were made into peeling processing.
The molded product of the present invention has an ASKER-C hardness meter having a hardness at 25 ° C. of 50 or less, preferably 40 or less. When the hardness of the molded body is higher than 50, the flexibility is lowered. Therefore, in order to ensure sufficient flexibility (flexibility), the hardness needs to be 50 or less.
Adjustment of the hardness of this molded object can be suitably adjusted with the ratio of the component A and the component B, the kind of liquid isocyanate compound which is the component C, and the kind and addition amount of a filler. The hardness of the molded body indicates the hardness when the curing reaction is completed.

In order to obtain a composition that is excellent in shear bonding performance at high temperature and can be used for bonding a site requiring heat resistance as a pressure-sensitive adhesive, the mixing ratio of each component in the present composition is appropriately selected. From such a viewpoint, it is preferable that the compounding ratio of the component A and the component B is A: B = 7: 3 to 1: 9 in mass ratio.
The molded body obtained from the present composition is excellent in heat resistance and at the same time has sufficient flexibility such as a hardness (25 ° C.) of 50 or less in an ASKER-C hardness tester, and has a non-curved surface and the like. It is a soft resin molded article excellent in followability to a flat surface.
Also in the shear holding test described later, in a shear holding test in a state where a load of 10 g / cm ² was applied to an adhesive area of 25 mm × 25 mm, 500 hours at 100 ° C., and even 1000 hours later, 2 The molded body in which the deviation from the initial position between the two aluminum plates does not occur can be obtained by curing the composition.
Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

1. Acrylic monomer and isocyanate compound Table 1 shows examples of acrylic monomers and examples of isocyanate compounds (especially, examples of trifunctional isocyanate compounds) that are raw materials for the compositions of the present invention and comparative compositions.

表２中、ＯＨＶ（％）は、水酸基価を意味する。 2. Solventless acrylic copolymer Examples of solventless acrylic copolymers which are the main ingredients of the compositions of the present invention and the compositions of comparative examples are shown in Table 2 below.

In Table 2, OHV (%) means a hydroxyl value.

3. Liquid isocyanate compounds Examples of liquid isocyanate compounds that are curing agents for the compositions of the present invention and the compositions of comparative examples are shown in Table 3 below.

4). Production of composition of the present invention Solventless acrylic copolymer (acrylic resin), liquid isocyanate compound, catalyst, antifoaming agent, dehydrating agent and light stabilizer shown in Table 4 below are the proportions (mass%) shown in Table 4. ), And after mixing and stirring, it was sufficiently degassed to obtain the composition of the present invention. The following were used for the catalyst, antifoaming agent, dehydrating agent, and light stabilizer.
Catalyst: “U-340”, Nitto Kasei Co., Ltd. defoaming agent: “SAG-47”, Nippon Unicar Co., Ltd. dehydrating agent: “Zeoram A3”, Tosoh Corporation light stabilizer: “Irganox 1135”, Ciba・ Specialty Chemicals Co., Ltd.

  This composition was uniformly coated on a polyester film whose surface was release-treated. After coating, it was cured by heating in an oven at 100 ° C. for 7 minutes. Furthermore, it was cured by leaving it to stand at room temperature for 24 hours to obtain a sheet-like main molded body.

5. Production of Composition of Comparative Example As in the Examples, the solvent-free acrylic copolymer (acrylic resin), liquid isocyanate compound, catalyst, antifoaming agent, dehydrating agent and light stabilizer shown in Table 5 below are shown in Table 5. It mix | blended by the ratio (mass%) shown, and after mixing and stirring, it defoamed enough and the composition of the comparative example was obtained.

  The composition of the comparative example was uniformly coated on a polyester film whose surface was release-treated. After coating, it was cured by heating in an oven at 100 ° C. for 7 minutes. Furthermore, it was cured by allowing it to stand at room temperature for 24 hours to obtain a molded article of a comparative example in the form of a heat conductive sheet.

6). Test of high-temperature shear bonding performance (holding ability of heat-resistant shear bonding force) (shear holding test)
The test (shear retention test) of the molded article of the present invention and the molded article of the comparative example was subjected to a method in accordance with JIS K 0237 8.3.3. It was. Hereinafter, the test method will be described with reference to FIG. As shown in FIG. 1 (a), a sheet-like molded body of the present invention and a comparative molded body were cut into a size of 25 mm × 25 mm (thickness 1.5 mm) to prepare a test piece 1, and two sheets Were sandwiched between aluminum plates 2 and 3 (dimensions: 30 mm × 100 mm, thickness 3 mm), and a force of 5 kgf (49 N) was applied for 15 minutes to bring them into close contact. One aluminum plate 2 of the laminate is fixed, and a 100 g weight 4 is hung on the other aluminum plate 3 and is heated in an oven at 100 ° C. (or may be tested at 80 ° C.). As shown in FIG. 1B, the initial position of the two aluminum plates [the position where the upper end of the aluminum plate 3 is projected onto the surface of the aluminum plate 2; L ₁ in FIG. 1B; For example, it is easy to understand if the end face of the aluminum plate 2 is marked with a line or the like] [the distance between L ₁ and L ₂ in the right side of FIG. 1B; in FIG. L ₂ was measured after the holding for 500 hours, the position where the upper end of the aluminum plate 3 was projected onto the surface of the aluminum plate 2; for example, it is easy to understand if a mark such as a line is attached to the end surface of the aluminum plate 2 . In addition, depending on the properties of the test piece 1, not only the two aluminum plates 2 and 3 are displaced as shown in FIG. 1 (b), but also may be accompanied by deformation of the test piece 1, all in the same manner, The deviation from the initial position between the two aluminum plates can be measured.

表６における評価の尺度は以下の通りである。
○：良い
△：普通
×：悪い
表６から明らかなように、実施例の組成物（番号１〜６）は硬化性が良いか又は普通で、且つ硬度は全て低く軟質である。また、諸物性のバランスが良好であることが判る（特に、番号１〜４の組成物）。これに対して、比較例の組成物（番号７〜１５）は、硬化性が悪いか又は硬度が高いものが多い。また、諸物性のバランスも悪いことが判る（例えば、番号７〜１５の組成物中、諸物性の評価において×が一つの無いものは皆無である）。 7. Physical property values of the molded body of the present invention and the molded body of the comparative example Table 6 below shows the physical property values of the molded body of the present invention and the molded body of the comparative example.

The scale of evaluation in Table 6 is as follows.
○: Good Δ: Normal ×: Poor As is apparent from Table 6, the compositions of the examples (Nos. 1 to 6) have good or normal curability and are all low in hardness and soft. Moreover, it turns out that the balance of various physical properties is favorable (especially the composition of numbers 1-4). On the other hand, the compositions of the comparative examples (numbers 7 to 15) often have poor curability or high hardness. Moreover, it turns out that the balance of various physical properties is also bad (for example, in the compositions of Nos. 7 to 15, there is no one having no single x in the evaluation of various physical properties).

  The soft resin molding of the present invention obtained from the composition of the present invention has both good flexibility and good heat resistance, and as a material to replace conventional vulcanized rubber, silicone rubber or gel, It can be applied to various uses that require maintaining excellent shear bonding performance over a long period of time at high temperatures.

It is a figure for demonstrating the test method (shear retention test) of the high temperature shear bonding performance of the composition for flexible resin moldings.

Explanation of symbols

1: Test piece 2, 3: Aluminum plate 4: Weight 5: Misalignment

Claims (6)

A: Solvent-free acrylic copolymer having a functional group containing 2.2 to 2.7 hydroxyl groups per molecule and having a number average molecular weight of 8000 to 30000 at room temperature,
B: Solvent-free acrylic copolymer containing 1.3 to 2.1 hydroxyl groups per molecule as a functional group and having a number average molecular weight of 2000 to 7000 and fluidity at room temperature, and C: A composition for a soft resin molded article containing a liquid isocyanate compound containing an isocyanate group as a functional group and having fluidity at room temperature. Component C is at least
C1: carbodiimide-modified methylene diphenyl diisocyanate,
2. A composition comprising C2: methylene diphenyl diisocyanate and C3: a prepolymer of methylene diphenyl diisocyanate and a diol, wherein the ratio of component C1 is 10 to 97% by mass based on the total mass of component C. The composition for soft resin moldings.   The composition for a soft resin molded article according to claim 2, further comprising an isocyanate compound containing at least three isocyanate groups in the molecule as Component C.   Component A or Component B is a solventless acrylic copolymer obtained from a monomer mixture mainly composed of a monomer having a boiling point of 200 ° C. or higher, wherein the monomer is 80 in the structural unit of Component A or Component B. The composition for a soft resin molded article according to any one of claims 1 to 3, wherein the composition is contained in an amount of not less than mass%.   The composition for a flexible resin molded article according to claim 1 or 2, wherein in the shear holding test, no deviation from the initial position between the two aluminum plates occurs even after 500 hours at 100 ° C. A soft resin molded body obtained by curing.   4. The composition for a soft resin molded article according to claim 3, wherein in the shear holding test, a deviation from the initial position between the two aluminum plates does not occur even after 500 hours at 100 ° C. A soft resin molding obtained by the above process.

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