JPS63182391A - Impregnating agent for porous rigid material - Google Patents

Abstract

PURPOSE:To prepare the title impregnating agent which, when infiltrated into a porous rigid material and heated, can hermetically seal the pores of the rigid material and completely prevent the leakage, by incorporating a non-shrinkable monomers comprising a bicycloorthoester or a spiroorthoester. CONSTITUTION:A non-shrinkable monomer (A) comprising a bicycloorthoester (a) of formula I (wherein R1 is H or a lower alkyl) [e.g., 1-vinyl-4-ethyl-2,6,7- trioxabicyclo(2,2,2)octane] or a spiroorthoester (b) of formula II (wherein n=1-3; and m=1-8) [e.g., 2-methylene-1,4,6-trioxaspiro(4,6)undecane] is optionally mixed with a (meth)acrylate (B). The mixture is then mixed with 0.1-5wt.% polymerization catalyst (C) [e.g., azobisisobutyronitrile], 0.001-2wt.% polymerization inhibitor (D) (e.g., hydroquinone), 0.5-20wt.% plasticizer (E) (e.g., a phthalate), etc.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention is a novel impregnating agent for porous rigid objects, more particularly for castings of aluminum alloys, zinc alloys, magnesium alloys, copper alloys, iron alloys, etc. The present invention relates to an impregnating agent that impregnates the surface and pores of porous rigid objects such as powder metallurgy sintered bodies and ceramics, and then hardens them to encapsulate and seal them.

Cast or sintered metals are widely used as various automobile parts and electromechanical materials, but since these metals generally have pores of various shapes called shrinkage cavities on their surfaces and insides, they must be used carefully. Pores that cause leakage must be sealed. Furthermore, when performing electroplating or chemical plating on a cast product or a sintered body, it is necessary to seal the defective parts exposed on the surface.

[Conventional technology and its problems]

Conventionally, various methods have been used to seal the pores of the above-mentioned porous rigid object, but among them, unsaturated esters, esters, etc. are used as impregnating agents. A commonly used method is to use a thermosetting resin raw material such as oxide, silicone, phenol, or Schiff 1flu7talate, polymerize and harden it in the pores, and then seal it. However, these impregnating agents have various drawbacks in terms of viscosity, curing conditions, etc., and are not always satisfactory.

On the other hand, impregnating agents containing small amounts of polyfunctional acrylic ester monomers and substantially the majority of (meth)acrylic ester monomers have been developed in recent years (for example, British Patent No.
, No. 297, 103, Special Publication No. 50-20989, Special Publication No. 3645-1974, etc.). These impregnating agents have the advantage of having low viscosity and penetrating power, adhering to the surface of rigid objects, and allowing the pre-metal impregnation liquid to be easily washed away with water. It can be easily cured at relatively low temperatures.

However, when a casting having pores is impregnated with such a (meth)acrylic acid ester impregnating agent to impart airtightness, it may not be possible to seal the pores successfully. That is, the shapes of blowholes are diverse and complex depending on the cause of their occurrence, but defects caused by hot melting, for example, have poor impregnation, and the sealing success rate of such parts may be extremely poor.

Furthermore, if the size of the shrinkage cavity at the defective part is expressed in terms of the amount of gas leakage (pressurized gas, td/mI n ) in the primary and secondary tests, the amount of leakage is several hundred! A defective part with a rate of 1 liter/min or more may not pass the test even if it is impregnated.

For defective parts with such a large amount of leakage, parts that had an extra-large leak before impregnation treatment became medium leaks, parts with large leaks became small leaks, and parts with large leaks became large leaks after the impregnation treatment. There is a general tendency that parts with small leakage are improved by 6D.
, − times of impregnation treatment will not pass the test. Moreover, even if an oversized leak were to pass the sealing process, the durability would be poor, and for example, in the case of automobile parts, leakage would occur unexpectedly quickly after installation. In the case of organic impregnating liquids, these various cases can be directly affected by the composition of the impregnating liquid, such as cracks during curing, stress strain of the cured product, closeness to rigid objects, outflow of the impregnant from pores, and volumetric shrinkage of the cured product. Due to performance.

Not all pressure leakage cast parts that have shrinkage cavities are subject to impregnation, but there is a certain limit to what can be repaired depending on the diameter of the shrinkage cavity that is the direct cause of the defect. has been done. However, parts that leak more than a certain amount are excluded from the impregnating target, and parts that do not pass the impregnation process are dissolved without being impregnated again.

Cracks in the polymerized cured product are caused by internal stress distortion caused by differences in the reactivity ratio or polymerization rate of the methacrylic acid ester as the main ingredient and the composition monomers such as the crosslinking agent. Further, the adhesion of the polymerized cured product to the metal it comes into contact with is based on the inherent affinity between the contained material and the metal. Furthermore, it is known that methacrylic acid ester resins, like general vinyl monomers, undergo large shrinkage during polymerization. .5
%, acrylonitrile 31%, vinyl acetate 21%, ethyl methacrylate 17.8%, methyl methacrylate 21.
2%, and sialyl phthalate 11.8%. This phenomenon is a big problem from the perspective of materials science, but especially for impregnants that impregnate porous rigid objects to make them airtight, the volumetric shrinkage rate during curing has an important effect on their performance. .

[Means for Solving the Problems] Under such circumstances, the present inventors have conducted intensive research and found that the following general formulas (I) and (shoulder), which are non-shrinkable monomers, are non-shrinkable monomers.
Bicycloorthoesters and spiroorthoesters represented by the above have excellent properties as an impregnating agent for porous rigid objects, and furthermore, the non-shrinkable monomer and (meth)
It was discovered that an excellent impregnating agent can be obtained by combining acrylic acid esters, and the present invention was completed.

Therefore, the present invention provides vinyl orthoesters represented by the following general formula (I) (in which % R1 represents a hydrogen atom or a lower alkyl group) or the following general formula (I) (in which n is The present invention provides an impregnating agent for porous rigid objects, which is characterized by containing a spiro-orthoester represented by the following (integer of 1 to 3, m is an integer of 1 to 8).

Furthermore, the present invention provides an impregnating agent for porous rigid objects containing the above-mentioned bicycloorthoester (I) or spiroorthoester (seal) and (meth)acrylic acid ester.

In the present invention, the bicycloorthoesters of formula (I) include, for example, 1-vinyl-4-2fk-2,6,7
-) rioxapicyclo(2,2,2)octane, 1-f
Lopenyl-4-methyl-2,6,7-)lioxapicyclo(2,2,2)octane, 1-butenyl-4-methyl-2,6,7-)lioxapicyclo(2,2,2)octane, etc. Examples of spiro-orthoesters of the formula (seal) include 2-)f-lene-1,4,6-)+Joxaspiro(4,6)undecane, 2-methylene-1°4.
6-)rioxaspiro(4,6)dodecane, 2-methylene-1,4,6-dorioxaspiro(4,6)decane, and the like.

The impregnating agent of the present invention contains (I) or (
Although the compound of formula I) can be used alone, it can also be used in combination with other polymerizable monomers. As other polymerizable monomers, any of those conventionally used as impregnating agents can be used, but among them (
Particularly preferred are meth)acrylic acid esters.

When used in combination with (meth)acrylic esters, (I)
or the compound of formula (I) is 10%w of the total polymerizable monomers
It is preferable that the amount of % (I) or the compound of formula (I) is less than this because the volumetric shrinkage rate will be large and the object of the present invention will not be achieved.

The impregnating agent of the present invention is produced by suitably blending the polymerizable monomer with a polymerization catalyst, a polymerization inhibitor, a plasticizer, etc. that have been commonly used in the past.

Examples of polymerization catalysts include radical polymerization catalysts such as benzoyl, Q-oxide, methyl ethyl ketone q-oxide, various alkyl/Q-esters, azobisisobutyronitrile, redox catalysts, and organometallic peroxides;
Metal halides such as BF, htct, C1, CC0
Examples include H donor substances such as OH, F, and CCoon, cationic polymerization catalysts such as pencil sulfonium salts, mu-tct, c, m, and the like. The radical polymerization catalyst and the cationic polymerization catalyst are preferably blended in an amount of O, OS ~5% w/w and 0.01~5% w/y of the total impregnating agent composition, respectively.

Examples of the polymerization inhibitor include substituted hydroquinones such as hydroquinone and methoxyhydroquinone, various alkylated phenols, and the like.
It is preferable to mix 0.001 to 2% W/w.

Examples of plasticizers include phthalate esters, phosphate esters, and plasticizers. Examples include xyl fatty acid esters, aliphatic dibasic acid esters, etc., and these account for 0.5 to 2 of the total composition of the impregnating agent.
It is preferable to mix 0% W/'IF.

To seal the pores of a porous rigid object using the impregnating agent of the present invention, a method known per se is employed. That is, a porous rigid object is immersed in an impregnating agent under reduced pressure to draw the impregnating agent into the pores, and then treated at 90° C. for about 10 minutes to polymerize the polymerizable monomer and seal the pores.

〔Effect of the invention〕

The polymerizable monomer of the impregnating agent of the present invention has no volume shrinkage due to polymerization, and the polymer has good adhesion to rigid objects, so the pores can be airtightly sealed and leakage can be completely prevented. Examples] Next, examples will be described.

Example 1 Preparation of impregnation agent: l-vinyl-4-ethyl-2,6,7-)lioxabicyclo(2,2,2)octane (polymerizable monomer of formula (r)) 50f, methacrylic acid 2- Hydroxypropyl 50F and trimethylolzolononine 9-trimethacrylate 10F were mixed and stirred, and this mixed solution was added with 0.1f of KP-methoxyphenol, 1r of pencilsulfonium salt, and 0.25t of azobisisobutyronitrile. Add, stir thoroughly, and dissolve to obtain an impregnating agent. When the impregnating agent thus obtained is heated to 90° C., it hardens and becomes a resin in approximately 4 minutes and 20 seconds.

Example 2 Preparation of impregnating agent: 2-methylene-1,4,6-)rioxasubilo(4,6
) Kundecane (polymerizable monomer of formula (I)) sop, 2-hydroxyzorogyl methacrylate 50F and trimethylolzolonon trimethacrylate 10f were mixed, stirred, and this mixed solution 4Cp-methoxyphenol 0.12
1 F of pensol sulfonicum salt and then 0.25 F of azobisisobutyronitrile are added and thoroughly stirred and dissolved to obtain an impregnating agent. When the impregnating agent thus obtained is heated to 90° C., it hardens and becomes a resin in approximately 3 minutes and 30 seconds.

Example 3 Impregnation treatment of a porous rigid object: (I) Nine pressure-leak die-cast products/gear cases with cavities that have been previously washed with a solvent and sufficiently dried are placed in an impregnation tank (autoclave), and after sealing, the tank is evacuated. ? 1 to 3 mmHfI/c: 1G empty with Nzo,
After holding for 15 minutes, the impregnating agent prepared in Example 1 (product of the present invention) is injected into the tank by the suction force of the vacuum in the tank until the casting inside is completely immersed. Next, after returning the impregnating tank to atmospheric pressure, it is pressurized to 6H/cx'' using compressed air from a compressor and held for 15 minutes.Then, the pressure is returned to atmospheric pressure again, and the impregnating liquid is drained from the impregnating tank. Remove the casting inside, drain the impregnating liquid that has adhered to it, and wash the impregnating liquid remaining on the surface using cleaning water or a solvent. Immediately after washing, wash it in K10 hot water at 90°C. The impregnating liquid filled into the pores was immersed for a minute to harden. After curing, a positive and negative test by submersion in water was conducted using compressed air (# for I, /II''). In addition, as a conventional product, methacrylic acid-2-hydroxy 7Or:1 pill (85
F),) trimethylolzolonone methacrylate (t
Using an impregnating solution consisting of p-methoxyphenol (0, IF) and azobisisobutyronitrile (0,25F), the same procedure as in the product of the present invention was performed.

Table 1 Original and sub-test results Test pressure (air) @ 1 'J/t* "Passed: No pressure leak observed (2) Aluminum wheels for automobiles are low-pressure cast products, but some defective products with pressure leaks due to shrinkage cavities occurred. In foundries, the amount of leakage is qualitatively displayed as extra-large, large-scale, large, medium, small, and trace amounts, and among these, unnecessary wheels with especially large leakage amounts of extra-large, large-scale, and large are selected and classified into three levels. The impregnating effects of the inventive product and the conventional product were compared in the same way as in (I).The results are shown in Table 2, and it is clear that the impregnating agent of the present invention has a remarkable effect. .

Margins below: Table 2 Original and Sub Test Results (3) The performance of the impregnating agents prepared in Examples 1 and 2 was compared with conventional products in terms of heat resistance and hydraulic oil resistance. For this test, an aluminum plate (material: AC4C aluminum alloy, plate thickness: IQ) with a through hole of 0.6 mm in diameter was used.
A test piece in which an impregnating agent was injected into the hole (mm) and cured was used as a test piece.

For the heat resistance test, the test piece was placed in a constant temperature bath (hot air circulation type) at 150° C., and a positive and negative test was conducted every 24 hours. The time required for pressure leakage of test pieces for each impregnating solution was compared. The test results are shown in FIG.

For the hydraulic oil resistance test, a test gear was placed in a constant temperature bath1.
It was immersed in engine oil at 25° C., and a positive and negative test was conducted every third day. The number of days until pressure leakage occurred for the test pieces of each impregnation solution was compared. The test results are shown in Figure 2.

From FIG. 1 and FIG. 2, it is proven that the product of the present invention is superior to conventional products in both heat resistance and hydraulic oil resistance.

Example 4 1-vinyl-4-ethyl-2,6,7-)lioxapicyclo(2,2,2)octane or 2-methylene-1,4
, 6-)Impregnating agents were prepared in the same manner as in Example 1 or 2, with different mixing ratios of rioxasubio(4,6)undecane and 2-hydroxy fQ pill methacrylate. The specific gravity of this impregnating agent was measured, and then a small amount of the impregnating agent was collected in a beaker and heated in 90°C hot water for 10 minutes to obtain a cured product.
This cured product is cut to a certain size, its volume and weight are measured, and the specific gravity is determined. The volume shrinkage rate due to polymerization is calculated from the specific gravity of the impregnating agent and the cured product. The results are shown in Table 3.

Margin below Table 3 Volumetric shrinkage rate

[Brief explanation of the drawing]

FIG. 1 shows the results of a heat resistance test of a test piece whose pores were sealed and sealed with the impregnating agent of the present invention, and FIG. 2 shows the results of a hydraulic oil resistance test of the same test piece. that's all

Claims (1)

[Scope of Claims] 1. Bicycloorthoesters represented by the following general formula (I) ▲Mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, R_1 represents a hydrogen atom or a lower alkyl group) Or spiroorthoesters represented by the following general formula (II) ▲Mathematical formulas, chemical formulas, tables, etc.▼(II) (In the formula, n is an integer of 1 to 3, m is an integer of 1 to 8) An impregnating agent for porous rigid objects characterized by containing. 2, (meth)acrylic acid ester, and the following general formula (
I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, R_1 represents a hydrogen atom or a lower alkyl group) Bicycloorthoesters or the following general formula (II) ▲Mathematical formulas, chemical formulas, There are tables, etc. ▼ (II) For porous rigid objects characterized by containing spiroorthoesters represented by (where n is an integer of 1 to 3 and m is an integer of 1 to 8) Impregnating agent.