JPH0679983B2 - Cellular ceramic reinforcement material - Google Patents

Description

The present invention relates to a reinforcing material (reinforcing ma) for structural materials.
terial), which also reduces weight, improves impact resistance and increases stiffness. In particular, the invention relates to reinforcing materials that maintain such properties over a wide range of temperatures.

[Conventional technology]

U.S. Pat. No. 4,610,836 [wycech]
States that it is known to reinforce structural materials by filling cavities with structural foam plastic [US Pat. No. 3,909,058].
Issue (Klammer) is quoted]. Wisek is 0.02-0.
Syntactic foam filled with hollow glass or plastic microspheres with a diameter of 15 mm has the same purpose, while also reducing weight, improving impact resistance and increasing stiffness. A granular mixture that is used and is mixed into a shaped cavity as taught in US Pat. No. 4,405,165 (Murphy) by mixing such microspheres with a curable thermosetting resin. Is also manufactured. Wisek's patent above has a large number of microspheres bound together to give 0.5-10mm
It is further stated that it is known to form large spheres having a diameter of 10 and fill the gaps between the large spheres with aggregate foam to provide a buoyant structure. The invention of the above Wisek patent is a glass large sphere coated with an adhesive sufficient to bond the large spheres to each other and to the structural material without filling the gaps between the large spheres. To meet. This allows the passage of air so that no water is trapped in the reinforcing structural material.

U.S. Pat. No. 4,737,407 (Wisek) discloses that large spheroids of glass microspheres and a phenolic binder are combined with a phenolic resin to increase strength and shell thickness, then B-staged phenol. It is stated that it can be coated with a system or epoxy resin to allow large spheres to be bonded together to form structural reinforcements. Examples of such large spheres are two materials manufactured by 3M under the following trade names: M27X for uncoated large spheres, and for phenolic resin coated large spheres. M35EX (column 1, lines 35-43). In fact, M
27X and M35EX refer to large hollow spheres of hollow glass microspheres and phenolic resin binders, as shown in US Pat. No. 4,111,713 (Beck). M3
The 5E "E" means that the large spheres have an epoxy resin coating. The true densities of M27X and M35EX are 0.27 and 0.35 g / cm ³ , respectively. These large microspheres are no longer manufactured and are clearly considered too expensive for most of their potential applications.

According to Wisek's U.S. Pat.No. 4,737,407, the conventional plastic reinforcement is a lightweight yet strong reinforcement,
It is stated that it was not possible to provide one that was thermally stable and competitive in cost with other types of structural reinforcements. The solution according to Wisek's US patent is
Extruding a mixture of expanded or unexpanded microspheres of organic material or glass and a thermosetting resin. After gelling the extruded string, it is cut into pellets. The pellets may include a blowing agent that allows the pellets to expand upon heating. The pellets are preferably coated with an adhesive before being formed into a structural reinforcement.

Another type of large spheroid is described in US Pat. No. 4,632,876 (Laird et al.). The patent has been assigned to 3M, the assignee of the present application. These large spheroids are in the form of cellular ceramic spheroids which together have great strength or crush resistance (due to the tough outer shell) and low density (due to the closed cellular microporosity). There is. Laird's cellular ceramic spheroids usually have a diameter of about 0.2-5 mm, they are 2.
Has a smaller density than 2 g / cm ^3, can be easily be made to have a 1 g / cm ³ less than the density. The Laird patent states that the cellular ceramic macrospheres can be bonded together by an organic material such as epoxy resin or an inorganic material such as cement. Aggregate foams and fillers are used in calcined gypsum, concrete, plastic, and ceramic products. The Laird patent description is included here for reference.

The Laird's patented cellular ceramic macrospheres, Macrolite (TM), are commercially available in various sizes from 3M. Ie: These Macrolite Cellular Ceramic Large Spheroids are 11
It is stable to long-term exposure to 00 ° C and has been used experimentally to reinforce materials in much the same way as the large spheres of Wisek U.S. Pat. No. 4,737,407 at much lower cost.

[Summary of the Invention]

The present invention is a lightweight reinforcing material, similar to the conventional methods described above, that can be used to strengthen structural materials while reducing weight, improving impact resistance, and increasing stiffness. Compared to the conventional reinforcement materials discussed above, the reinforcement materials of the present invention are less expensive than the conventional ones which are not based on cellular ceramic macrospheres. Compared to conventional reinforcing materials based on cellular ceramic macrospheres, those of the present invention provide substantially greater strength.

Briefly, the reinforcing material of the present invention is at least 0.
It consists of cellular ceramic large spheres with a diameter of 2 mm and a binder which is a mixture of hollow microspheres and an adhesive.
The microspheres preferably have a diameter of 1-160 μm, a true particle density of less than 0.6 g / cm ³ and should constitute less than 20% by weight of the binder. The binder comprises 10 to 50% by weight of the reinforcing material.

The average diameter of the cellular ceramic large spheres is preferably 1-3 mm. For particle sizes substantially larger than that,
The new reinforcing material may not be able to completely reinforce the small cavities and gaps. On the other hand, the use of cellular ceramic large spheres substantially larger than 3 mm can reduce the cost of the new reinforcing material by minimizing the proportion of binder. Diameters up to 25 mm have been found to be useful, especially to form large bricks.

Substantially less than 1 mm average diameter of ceramic large spheres requires a larger proportion of binder to achieve the same strength at large surface areas, thus increasing the density and cost of the new reinforcing material. .

It is preferred that the hollow microspheres are glass. Because they are cheaper than plastic microspheres, they can also give the new reinforcing material both better compressive strength and better high temperature resistance. The average diameter of the microspheres is preferably 20-80 μm. Substantially larger microspheres are not currently commercially available and will be more expensive. Substantially smaller microspheres tend to give undesirably high densities when used in new reinforcing materials,
It will be necessary to use a large proportion of binder. The true particle density of the microspheres is greater than 0.5 g / cm ³ in order for the reinforcement product of the present invention to be strong and light in addition to being capable of absorbing the forces that occur in collisions. It is preferably small.

The microspheres should make up less than 20% by weight of the binder. At higher proportions, the binder becomes too viscous and difficult to mix with the ceramic spheroids. The microspheres preferably make up at least 2% by weight of the binder. This is because beneficial effects such as weight loss and increased compressive strength become almost negligible at substantially lower rates. More preferably, the microspheres comprise 5-10% by weight of the binder.

When high structural strength and stiffness are important, the binder adhesive is a thermosetting resin that can be cured to a strong and tough state, as with most epoxy and phenolic resins. It is preferably a composition. When elasticity and energy absorption are important, thermosetting resin compositions are preferred because they cure to a soft and flexible state, like most polyurethanes. For example, thermoplastics such as vinyl polymers have also been found to be useful as adhesives.

By limiting the amount of binder to 50% by weight or less of the reinforcing material, the spacing between adjacent ceramic large spheres tends to be less than or equal to the average diameter of the microspheres. Substantially greater proportions would result in undesirably large spacing between adjacent ceramic large spheres, reducing both compressive strength and high temperature resistance. Moreover, the reinforced products of the present invention have a high density and impede the passage of air, so that the important object of the present invention will not be achieved. On the other hand, if the binder is substantially below 10% by weight of the reinforcing material, the reinforced product of the invention will have poor compressive strength.

When the proportion of binder is 10-40% of the new reinforcing material used to reinforce the structural material, the resulting reinforcing material has three types of energy absorbing voids: 1) Cellular ceramic An internal cavity structure within each of the large spheres,
2) Hollow portions within each microsphere of binder and 3) interstitial spaces between the coated large spheres. Therefore, in the event of a collision
The stiffener can collapse in each of these three types of voids, thereby gradually absorbing the impact force. Where the proportion of binder is high, the reinforced product has a high structural strength, but with some small energy absorption, in some applications the proportion is high enough that the reinforced product of the invention is It may be preferable to have no intervening gaps.

To formulate the new reinforcing material, the microspheres may first be evenly dispersed in a liquid adhesive such as a thermosetting resin composition to provide the binder. The binder can then be mixed into a group of ceramic macrospheres to provide a coating thereby forming the binder-coated macrospheres into a reinforced article such as a shaped body. Another compounding method that has been found to be useful is to mix the resin portion of the two-part thermosetting resin composition with the microspheres and coat the mixture on a ceramic large sphere before , Mixing the curing agent for the thermosetting resin with the coated large spheres. Alternatively, a hardener is coated on the cellular ceramic large spheres,
Thereafter, the mixture of resin and microspheres may be coated onto the hardener coated large spheres.

The new reinforcing material can be injected into the cavities of the structural material and then cure the adhesive in the binder, bonding the large spheres to each other and to the walls of the cavities.

Instead of injecting the new reinforcing material into the cavity of the structural material, the vehicle manufacturer molds a molding that fits into the structural material from the reinforcing material and mechanically or with a bead of adhesive. Alternatively, a method of fixing in the cavity using a sheet may be selected. This prevents contamination around the assembly process and allows better alignment with the normal assembly process procedure.

[Detailed description]

The preferred cellular ceramic large spheroids for use in the reinforcing material of the present invention are the Laird's patented cellular ceramic large spheroids, such as Macrolite cellular ceramic large spheroids from 3M Company.

Preferred hollow microspheres are made of glass, for example
Scotchlite ™ glass microspheres from 3M Company.

The preferred adhesive for use in the binder is a thermosetting resin composition that, after curing, provides good strength and toughness while resisting degradation when exposed to high temperatures. Thermoplastic adhesives are also used as adhesives, but thermosetting resins are more suitable for applications involving exposure to the high temperatures commonly encountered in automotive, aircraft, and spacecraft applications. Not having a tendency.

The present invention may be more easily understood with reference to the drawings.

The cellular ceramic large spheres (10) shown in FIG. 1 have a coating of binder (12). Binders, adhesives (16)
It contains a large number of hollow microspheres (14) uniformly dispersed therein.

In FIG. 2, the U-shaped structural material (20) forms a cavity in which a reinforcing material containing cellular ceramic macrospheres (10) bound together by a coating of a binder (12) is provided. Are satisfied. FIG. 3 shows the inside of the large spherical body and the hollow microsphere inside each of the inner cavity structures, and between the coated large spherical bodies and between the coated large spherical body and the wall of the structural material (20). It indicates that there is an intervening gap (22).

FIG. 4 is described in Example 1 below. In the following examples all parts are by weight. The product of the example is ASTM C39-
Tested for compressive strength according to 86 and stiffness calculated from the initial slope of the stress-strain curve.

Example 1 In this example, cellular ceramic macrospheres (Macrolite ML714 from 3M); hollow glass microspheres with an average diameter of 50-70 μm (Scotchlite C15 / 25 from 3M).
0 glass microspheres); and 2 parts of a two-part liquid bisphenol / epichlorohydrin epoxy resin (Epon "Epon" 828 from Shell Chemical Co.) and 1 part of a diethylenetriamine-containing curing agent. Adhesive, aromatic hydrocarbon oil, and nonylphenol were used. The glass microspheres and adhesive were mixed together using a propeller mixer to give a binder containing 13% microspheres. The binder was mixed with ceramic macrospheres in a low shear mixer to form an injectable aggregate. This was poured into a cylindrical paper container, vibrated on a vibrating plate having a plunger, and packed to make uniform filling. Next, the container 12
The epoxy resin composition was allowed to cure in a 1 ° C. oven for 2 hours, thereby forming a cylindrical compact sample having a binder content of 28%.

This compact was tested in comparison with two other compacts made in the same manner except that the glass microspheres were omitted. The results are shown in Table I.

Figure 3 of the Drawing Another molded body sample was made in the same manner as in Example 1. However, the amount of binder was changed so that the glass microspheres occupied 10% of the binder. The compressive strength of the compacts, as reported in Table II below, are plotted in the squares in Figure 3 of the drawing, thereby plotting the curve (30) in Figure 3.

For comparison, molded articles were made in the same manner as Comparative Example B, except that the amount of binder was changed. Their compressive strengths, as reported in Table II below, are plotted as circles in Figure 3 of the drawing, thereby plotting curve (32) in Figure 3.

Table II Molds containing glass microspheres: Binder (%) 18 27 36 45 Compressive strength (MPa) 4.6 5.5 11.3 15.0 Molds excluding glass microspheres: Adhesive (%) 14.3 25 33.3 Compressive strength (MPa) 3.8 4.4 5.2

[Brief description of drawings]

FIG. 1 shows a cellular ceramic macrosphere having a binder coating of adhesive and hollow glass microspheres, together with a number of similar binder-coated ceramic macrospheres to provide the reinforcing material of the present invention. It is a schematic sectional drawing which passes along a spherical body. 2 is a partial schematic cross-sectional view of a structural material having a cavity filled with a reinforcing material made from many of the binder-coated ceramic large spheres of FIG. FIG. 3 is a partially enlarged sectional view taken along line 3-3 of FIG. FIG. 4 is a graph showing the influence of a change in the binder content on the compressive strength of a molded body made using the reinforcing material of the present invention. 10 …… Large spherical body, 12 …… Binder coating, 14 …… Hollow microsphere, 16 …… Adhesive, 20 …… Structural material, 22 …… Gap.

Claims (10)

[Claims] 1. A reinforcing material comprising a cellular ceramic large sphere having a diameter of at least 0.2 mm and a binder comprising a mixture of hollow microspheres and an adhesive, said microspheres comprising 20
Having an average diameter of -80 μm and a true particle density of less than 0.6 g / cm ³ , accounting for 2-20% by weight of the binder, the binder accounting for 10-50% by weight of the reinforcing material. Reinforcing material. 2. The method according to claim 1, wherein the adhesive is a thermosetting resin composition. 3. Cellular ceramic large spheres with a diameter of at least 0.2 mm, hollow microspheres with an average particle size of 20-80 μm, a true particle density of less than 0.6 g / cm ³ , and said microspheres with respect to each other. It consists of an adhesive that binds to and bonds to a large sphere, and the microspheres still have a total of 2 of the microspheres and the adhesive.
A reinforcing material molded body that occupies -20% by weight, and the total amount of the microspheres and the adhesive accounts for 10-50% by weight of the molded body. 4. The reinforcing material molded body according to claim 3, wherein the adhesive is a thermosetting resin. 5. The total of microspheres + thermosetting resin is 40
A reinforcing material shaped body according to claim 3, which is less than wt% and in which there are voids between the coated large spheres, which allows air to flow through the shaped body. 6. A) Dispersing hollow microspheres in a liquid adhesive to give a homogeneous binder, said microspheres being 20-80 .mu.m.
Having a mean particle diameter of less than 0.6 g / cm ^{3 and} a true particle density of less than 0.6 g / cm ³ and accounting for 2 to 20% by weight of said binder, and b) coating a group of cellular ceramic macrospheres with said binder. However, the binder makes up 10 to 50% by weight of the reinforcing material obtained, and at least the large spheres are at least
A method of manufacturing a reinforcing material with a diameter of 0.2 mm, comprising a continuous process. 7. A liquid adhesive is a resin part of a two-part thermosetting resin composition, and following step b), a coated large spherical body and a hardening agent part of the thermosetting resin composition. 7. The method of claim 6, wherein the step of mixing is performed. 8. The liquid adhesive is a resin part of a two-part thermosetting resin composition, and the large spherical body is mixed with the curing agent part of the thermosetting resin composition before step b). The method according to claim 6, wherein the step of performing is performed. 9. A method of reinforcing a structural material formed with cavities, comprising: a) a cellular ceramic large spheroid having a diameter of at least 0.2 mm, an average diameter of 20-80 μm and a true diameter of less than 0.6 g / cm ³ . A reinforcing material molded body composed of hollow microspheres having a particle density and an adhesive that bonds the microspheres to each other and bonds to a large spherical body, and the microspheres are 2 to 20 in total of the microspheres and the adhesive. A reinforcing material compact, which accounts for 10% by weight and the total of the microspheres + adhesive accounts for 10 to 50% by weight of the compact, is inserted into the cavity, b) the compact on the wall of the cavity A method of reinforcing structural materials that consists of various steps of adhesive bonding. 10. An average diameter of a large ceramic spherical body is 1 to
The method according to claim 9, which is 3 mm.