JPH0222765B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to epoxy resin compositions. More specifically, the present invention relates to a paste-like epoxy resin composition that is excellent in terms of workability in plating and the like. For models and jigs and tools of automobiles, ships, etc.,
Epoxy resin is often used, and for example, paste epoxy resin is applied to a substrate such as wood, FRP, foam, metal plate, etc., and the cured product is cut to create master models, vacuum molding molds, etc. There is. When an epoxy resin is used as a composition for this type of use, it is required to have the following properties. (1) The uncured epoxy resin composition has excellent mounting workability. In order to provide ease of plating work, it is necessary to make the epoxy resin composition into a paste, but conventionally the method used was to mix inorganic fillers such as metal powder with liquid epoxy resin for the purpose of making a paste. However, it is difficult for a cured product made from such a paste-like composition to have a high level of balance among the various properties required of the cured product as described below. For example, if a large amount of inorganic filler is added to improve the workability of plating, flexibility will inevitably decrease. If finely powdered silica, which is a thixotropic agent, is used in combination with metal powder, etc., the amount of metal powder used can be reduced and flexibility can be improved. Foaming properties and release properties are still insufficient. (2) The cured product must have flexibility (low compression modulus) In particular, large master models are often used to create an inverted model (resin mold or plaster mold) from this master model. For this reason, if it lacks flexibility, the master model is likely to be damaged during mold release work, or cracks will often occur due to the difference in coefficient of expansion with the substrate on which it is mounted or due to shrinkage stress during curing. (3) The cured product has good dimensional stability and machinability.As a result of various studies in search of a paste-like epoxy resin composition that simultaneously satisfies these requirements, the present inventors developed a blend of polyolefin-based synthetic pulp. was found to be extremely effective. Accordingly, the present invention relates to a paste-like epoxy resin composition, which comprises a liquid epoxy resin, a curing agent thereof, a metal powder, and a polyolefin-based synthetic pulp. The liquid epoxy resin that is the main component of the composition includes various types such as polyglycidyl ether, polyglycidyl ester, and alicyclic epoxy resin, but bisphenol A, bisphenol F,
Typical examples include glycidyl ethers of polyhydric phenols such as novolak, and brominated products thereof that are liquid at room temperature. These liquid epoxy resins generally have an epoxy equivalent weight of approximately
A range of 50 to 600 is used. As a curing agent, almost any curing agent that is generally used for curing epoxy resins can be used, but those that cure at room temperature and are liquid at room temperature are preferably used; for example, polyamine-based, polyamide-polyamine-based, etc. The use of hardeners is preferred. Examples of metal powder include aluminum powder,
Iron powder, copper powder, zinc powder, etc. are preferably used. Among these metal powders, it is recommended to use those with a particle size of 100 mesh passes or more in terms of machinability and polishability of the cured product, as well as surface finish and dispersibility. Most desirable. Various components are selected from the above ingredients depending on the performance required of the cured product. For example, for applications such as automobile master models, machinability, dimensional stability, flexibility, etc. are required, and for vacuum forming molds, in addition to these properties, materials with good thermal conductivity are required. To be elected. The blending ratio depends on the type and viscosity of the resin and hardening agent used, as well as the type, particle size, oil absorption amount, etc. of the metal powder, but in the case of metal powder, liquid epoxy resin, hardening agent and about 50 to 400 parts by weight, preferably about 100 to 200 parts by weight, per 100 parts by weight of the total amount of optional liquid components. If metal powder is used in a proportion higher than this, when it is made into a paste, it will not spread well during the application process, and its adhesion to substrates such as metal plates will also be poor, and the cured product will have a high modulus of elasticity. Flexibility is lost and cracks are more likely to occur when external stress is applied or due to internal stress. On the other hand, if less metal powder is used, a large amount of polyolefin-based synthetic pulp will inevitably be used to make a paste, and in this case, the machinability of the cured product, especially the polishability and dimensional stability, will be affected. The properties and thermal conductivity deteriorate, making it impossible to satisfy the required performance. Polyolefin-based synthetic pulp is manufactured from homopolymers or copolymers such as ethylene and propylene. For example, when polyethylene is used as a raw material, a pulp with a melt index of about 5 to 30 is dissolved in a solvent under heating. For surface treatment, it is possible to add a hydrophilic substance such as polyvinyl alcohol, flash it in water, and precipitate it under strong shearing force.In this case, by selecting various conditions, The shape and physical properties of the fibers can be varied within a wide range. Moreover, various commercially available products can also be used as they are. The synthetic pulp used in the present invention preferably has an average diameter of about 0.1 to 10 μm, an average fiber length of about 0.1 to 0.6 mm, and a water loss coefficient of about 0.03 to 8 seconds/g. Here, the average fiber length of the synthetic pulp is preferably within the above range from the viewpoint of dispersibility during mixing and workability in plating the paste composition, and the water coefficient is
It is shown as a value measured by the method specified in TAPPI-T221. Polyolefin synthetic pulp has a total content of liquid epoxy resin, curing agent, and liquid optional ingredients of 100%.
About 2 to 15 parts by weight, preferably about 5 to 12 parts by weight
Used in parts by weight. If synthetic pulp is used in a proportion higher than this, the proportion of metal powder will be reduced in order to maintain the paste-like composition, and the machinability of the cured product, especially its surface polishability and dimensional stability, will deteriorate. This worsens and becomes a problem when used for purposes such as master models. The composition is prepared by adding a flame retardant such as antimony, a plasticizer to improve the flexibility of the cured product or adjust the viscosity of the paste, a reactive diluent, and a non-reactive diluent to each of the above ingredients as necessary. This is carried out by appropriately adding a reactive diluent and the like, and then mixing using a mixer or the like. The paste-like epoxy resin composition according to the present invention can be plated on a substrate such as a metal plate such as an iron plate, wood, or plastic foam to any thickness, for example, a thickness of 20 mm or more, and has a so-called plating performance. It not only has excellent properties, but also excellent defoaming properties, release properties, and elongation. Curing is generally carried out at room temperature for about 1 to 24 hours, but in order to further improve the performance of the cured product,
Preferably, heating is carried out at about 60-150°C for several hours. Since the cured product has excellent flexibility and machinability, it can be easily processed into a desired shape, making it easy to manufacture large master models and vacuum molds for, for example, automobiles and ships. Next, the effects of the present invention will be explained with reference to Examples. Example 1

[Table] Each compounded component in the above ratio was kneaded for 20 minutes using a universal mixer to prepare a paste-like epoxy resin composition. This paste-like composition does not lean when placed on a vertically placed iron plate, can be applied thickly to a thickness of 20 mm or more, is less likely to form internal cavities, and is easy to apply when placed on a plate, such as peeling off or stretching. In good condition. In addition, the compressive elastic modulus of the cured product cured at room temperature for 1 day at -80°C for 1 hour (initial elastic modulus calculated by drawing under the same conditions as the compressive strength measurement method of JIS K-6911) is 11 Kg / mm It was ² . Comparative Example 1 In Example 1, an epoxy resin composition was prepared without using polyethylene pulp. This epoxy resin composition was in liquid form, and it was impossible to package it. Moreover, the compressive elastic modulus of the cured product was 10 Kg/mm ² . A comparison between Example 1 and Comparative Example 1 shows that the flexibility of the cured product, as indicated by the compression modulus, does not decrease even when polyethylene pulp is added. Comparative Example 2 In Example 1, a paste-like epoxy resin composition having a similar viscosity was prepared by increasing the amount of aluminum powder to 240 parts by weight without using the polyethylene synthetic pulp. This paste-like composition was inferior to that obtained in Example 1 in terms of plating workability, and the compressive modulus of the cured product was 86 kg/
mm ² , and a significant decrease in flexibility was observed. Comparative Example 3 In Example 1, 11.2 parts by weight of finely powdered silica (Aerosil 300 manufactured by Nippon Aerosil), which is commonly used as a thixotropic agent, was used instead of the polyethylene synthetic pulp to create a paste with a similar viscosity. An epoxy resin composition was prepared. The compressive modulus of the cured product is 10Kg/ ^mm2 ,
Although flexibility was maintained, the workability of plating was very poor in terms of defoaming properties and ease of removing by hand. Comparative Example 4 In Example 1, powdered silica (Tatsumori product Crystallite A-1) was used together with aluminum powder without using polyethylene synthetic pulp. In order to prepare a pasty epoxy resin composition having a similar viscosity, a large amount of silica, 132 parts by weight, is required, and its use is not suitable for adjusting the viscosity. Moreover, the compressive elastic modulus of the cured product was 24 Kg/mm ² and the flexibility was also reduced. Comparative Example 5 In Comparative Example 4, calcium carbonate (Tatsumori Product Whiten) was used for the same purpose instead of powdered silica.
P50) 168 parts by weight were used. The compressive modulus of the cured product was 25 Kg/mm ² . Example 2 In Example 1, iron powder (Dowa iron powder product; 250 mesh pass product) was used instead of aluminum powder.
168 parts by weight were used. The obtained paste-like epoxy resin composition had the same good plating workability, and the compressive modulus of the cured product was 28 Kg/ ^mm2 , which was better than that of Comparative Example 6 below. It shows good flexibility. Comparative Example 6 In Example 2, a paste-like epoxy resin composition having a similar viscosity was prepared by adding 400 parts by weight of iron powder without using the polyethylene synthetic pulp. This paste-like composition has poor workability in plating in terms of elongation, and the compressive modulus of the cured product is
It was 84Kg/ ^mm2 .

Claims (1)

[Scope of Claims] 1. A paste-like epoxy resin composition comprising a liquid epoxy resin, a curing agent thereof, a metal powder, and a polyolefin synthetic pulp. 2. The epoxy resin composition according to claim 1, wherein 50 to 400 parts by weight of metal powder is used per 100 parts by weight of the total amount of liquid epoxy resin, its curing agent, and liquid optional components. 3. The epoxy resin composition according to claim 1, wherein 2 to 15 parts by weight of polyolefin synthetic pulp is used per 100 parts by weight of the total amount of liquid epoxy resin, its curing agent, and liquid optional components.