JPH0664405A - Resin wheel for caster rubber wheel and caster rubber wheel - Google Patents

Abstract

PURPOSE:To provide a resin wheel and a rubber wheel utilizing the resin wheel capable of absorbing easily dispersion of outside diameters of bearings and having excellent adhesive property with rubber part and excellent impact strength. CONSTITUTION:A resin wheel comprises the step of mixing materials which comprise 100 parts of liquid thermo-setting resin (unsaturated polyester, vinyl ester and others), 5-20 parts of bridge formation having average grain size not more than 200mum or partially gridge-formed rubber grain (NBR, SBR, EPDM and others), 50-200 parts of reinforcing fiber (12-24mm long glass fiber), 200 parts of inorganic filler (calcium carbonate), 20 parts of plasticizer (styrene), 2 parts of cross linking agent (dicumyl peroxide), mold release agent, and thickener, and step of forming them into a specified form, which is stiffened to make the resin wheel, which has rubber grain condensed on the surface, charpy impact strength not less than 36kgf/cm<2> and 0.2mm interference fit, and no damage. Caster rubber wheel comprises a rubber part formed adhesively on the side periphery of the resin wheel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber wheel for a caster and a resin foil used for the same. More specifically, when mounting a bearing essential to the caster on the resin foil, the outer diameter of the bearing can be easily varied. The present invention relates to a resin foil that can be absorbed and is excellent in adhesion to a rubber portion and excellent in impact strength, and a rubber wheel using the same.

[0002]

2. Description of the Related Art As a conventional foil of this type, rust prevention,
Resin-made ones are known because of their light weight and low cost. Of these resins, in the thermoplastic resin foil,
Since the elongation at break becomes as large as 5% or more, a slight variation in the outer diameter of the bearing can be absorbed by press-fitting the bearing in the "shrink fit" direction. However, due to the lack of surface activity of the thermoplastic resin itself, the adhesive force with the rubber tire is weak, and it is necessary to use mechanical bonding (Japanese Utility Model Publication No. 57-32882). This makes the structure complicated, and even in this case, the reliability with respect to a high thrust load is essentially not sufficient.

[0003]

Further, in the above thermosetting resin foil, the molecular chains are three-dimensionally chemically bonded (crosslinked), so that the adhesion to the vulcanized rubber is easy and strong. However, the elongation at break is as small as 1% or less, and is effectively about 0.5%. If the bearing cannot be fitted when the bearing is press-fitted or if it is forcibly fitted, the foil will be easily damaged. Invite. For example, in the foil shown in FIG.
When the wheel inner diameter is 19.90 mm, the breaking dimension is 19.
90mm x 1.005 = 20.00mm, but this bearing is generally ± 0.1mm in variation and 20m in outer diameter.
In case of m needle bearing, φ20.00mm ±
It has a normal distribution of 0.1 mm (Fig. 5). Therefore, if they are fitted as they are, about 50% of the foils result in non-fitting bearings or foil breakage. In addition, if the dimensional variation of the bearing is within the dimensional tolerance range of the wheel inner diameter,
Although this problem can be solved, the cost is significantly increased and it is not practical. Furthermore, in order to obtain a material having a large elongation at break while maintaining high impact strength, a large amount of unvulcanized rubber component which is liquid or diluted in a solvent is added to the thermosetting resin to make the polymer matrix rubber-like. It is also known to give properties ("Polyester Handbook",
Page 84, published by Nikkan Kogyo Shimbun). However, this is not sufficient in terms of impact resistance, although a high elongation at break is obtained, and is as small as about ²⁰ kgfcm / cm ² .

The present invention solves the above-mentioned problems, and a resin foil capable of easily absorbing variations in the outer diameter of a bearing, and having excellent adhesiveness to a rubber portion and impact strength,
And to provide a rubber wheel using the same.

[0005]

Means for Solving the Problems The inventors of the present invention diligently studied how to fit a commercially available bearing having a large outer diameter variation to a reinforced thermosetting resin foil used for an ideal industrial caster without waste. It was obtained by doing. The resin foil used in the rubber wheel for casters of the present invention has 100 parts by weight of liquid thermosetting resin and an average particle size of 20.
Cross-linked or partially cross-linked rubber particles of 0 μm or less 5
20 parts by weight, reinforcing fibers, an inorganic filler, a plasticizer and a raw material containing a cross-linking agent are mixed, molded into a predetermined shape, and then cured to produce the rubber particles on the surface side in a concentrated form. Characterize.

The above-mentioned "liquid thermosetting resin" is an oligomer which shows a liquid state before heating, and examples thereof include liquid polyester resins such as unsaturated polyester resin, vinyl ester resin and epoxy acrylate resin. The thermosetting resin improves the tensile strength and the compressive strength after heating. In addition, "liquid" means that the raw material materials are easily mixed with each other, and when the rubber particles are mixed with a mixer, the rubber particles can be easily and uniformly dispersed, and the same crosslinking mechanism is used. This is because the blending is possible because it has

The above-mentioned "reinforcing fiber" is added to improve durability, and examples thereof include glass fiber, aramid fiber, carbon fiber and vinylon fiber. This fiber generally has a length of 12 to 24.
Long fibers of about mm are preferable. The blending amount of this fiber is preferably about 50 to 200 parts with respect to 100 parts of the thermosetting resin. If it is less than 50 parts, sufficient strength cannot be obtained, and specifically, the Charpy impact strength (hereinafter referred to as impact strength) according to JIS K6911 method is 35 kgfcm / cm ² or less, which is a standard of impact strength. If it exceeds 200 parts, the elongation at break may decrease to 0.5% or less, which is not preferable. The elongation at break of the unreinforced thermosetting resin is around 1% and the impact strength is 10 kg.
It is not more than fcm / cm ² .

The "inorganic filler" may be calcium carbonate, clay or the like, the "hardener" may be dicumyl peroxide, t-butylbenzoate or the like, and the "plasticizer" may be styrene monomer or acetone. Etc. can be used. In addition, a pigment such as carbon black, a thickener such as magnesium oxide, a release agent such as zinc stearate, and the like are added as necessary.

The "rubber particles" have an average particle size of 200 μm.
The following are crosslinked or partially crosslinked. The material of "rubber" here is NBR, SBR, EPD
M, IR, natural rubber and the like can be mentioned. Among these, NBR and SBR are preferable because they have a good balance of strength and weather resistance. On the other hand, when thermoplastic resin particles that show elastomeric behavior such as polystyrene or polyethylene are used instead of rubber particles, the fitability of the foil is almost satisfied, but the deterioration of heat resistance or durability. When the thermoplastic resin particles migrate to the molding surface, the adhesiveness between the foil surface and the rubber portion decreases. In addition, the use of "crosslinked or partially crosslinked" rubber particles prevents swelling and dissolution of the rubber particles by the liquid resin after compounding the molding material, and thus prevents the rubber component from liquefying. This is because the function of the rubber particles is maintained for a long time and the characteristics of the molding material are maintained.

Further, the reason why the rubber particles have an average particle diameter of 200 μm or less is that if the particle diameter exceeds this, it is difficult to transfer the rubber particles to the surface layer of the foil only by molding conditions. Also, the finer the particle size, the more uniform the dispersion becomes possible, which is preferable, but industrially 100 μm.
Something is supplied, and less than this is difficult to obtain. Further, if the average particle diameter is increased, it is convenient for migration, but the effect as a foreign substance is increased accordingly, and therefore, mechanical strength and impact strength may not be excellent in some cases. Further, the compounding amount of the rubber particles is set to 5 to 20 parts with respect to 100 parts of the liquid resin. If it is less than 5 parts, the addition effect is poor, while if it exceeds 20 parts, the matrix resin has rubber-like properties. The impact strength is still 3
This is because it becomes 5 kgfcm / cm ² or less.

When the resin foil of the present invention is molded and cured using a predetermined raw material composition, it is usually 140 to 160 ° C.
In the mold, a pressure of 50 kg / cm ² or more is applied under curing conditions of 1 to 5 minutes. In the present invention, at this time, the thermosetting resin utilizes the property that the material is melted from a semi-solid state to a liquid state immediately before curing and then solidified. That is, in the usual molding of thermosetting resin, particularly in compression molding, when the matrix contains extremely poor compatibility (for example, polyethylene fine particles or glass balloons not surface-treated), bumping When molding (gas demolding), there is a property that when pressed under a low-viscosity state immediately before curing, these will migrate to the surface layer as foreign matter. Not causing it is the original preferable molding. On the other hand, the present invention focuses on this property and produces a resin for foil having a functionally graded property. That is, the rubber particles uniformly mixed in the predetermined liquid resin,
It is exactly the above-mentioned incompatible foreign matter, and as a result of molding, the rubber particles are in a state of being transferred to the surface layer of the resin foil (Fig. 1). The thickness of the surface layer depends on the molding conditions, but is usually less than several mm.

The rubber wheel for casters according to the second aspect of the present invention comprises the resin foil according to the first aspect of the present invention and a rubber portion joined to the side peripheral surface of the resin foil via an adhesive layer. Characterize. The adhesive used is not particularly limited,
For example, synthetic rubber type, phenol resin type and the like can be used. The rubber component constituting the rubber portion is not particularly limited, but NR, BR and the like are preferable, and they are manufactured by molding and vulcanization.

[0013]

EXAMPLES The present invention will be specifically described below with reference to examples. (1) Production of Resin Foil Examples 1 to 7 First, the unsaturated polyester resin, plasticizer, curing agent, release agent, thickener and rubber particles shown in Table 1 (Examples 1 to 7) are shown in the same table. The ingredients were blended in the composition ratios shown below and thoroughly mixed and dispersed by a mixer. After that, a reinforcing fiber and an extender shown in the same table were added to the mixture in a kneader at a composition ratio shown in the same table and kneaded to prepare a molding material.

[0014]

[Table 1]

The composition components shown in the same table were as shown below. The numerical value showing the blending amount is parts by weight. "Unsaturated polyester resin"; Japan Yupica, trade name "Yupica""Vinyl ester resin"; Showa High Polymer Co., Ltd., trade name "lipoxy""Epoxy acrylate resin"; Japan Yupica, trade name "Neopol"

"Rubber particles"; Examples 1, 4, 6 and 7 = manufactured by Polycer, trade name "Clinac" Example 2 = SBR 100 parts, silica 30 parts, zinc white 5
Parts, stearic acid 1 part, vulcanization accelerator 0.5 parts, sulfur 2
The rubber powder obtained by cross-linking the rubber compound containing 10 parts of the rubber composition at 160 ° C. for 10 minutes is frozen in liquid nitrogen and then finely ground by a pulverizer to obtain rubber powder, which is then passed through a 200-mesh sieve to obtain an average particle diameter. 160 μm rubber particles Example 3 = 100 parts EPDM, 40 parts calcium carbonate,
A rubber cured product obtained by crosslinking 1 part of stearic acid, 5 parts of zinc oxide and 5 parts of dicumyl peroxide at 160 ° C. for 15 minutes was pulverized according to Example 2 to give an average particle size of 160 μm.
Example 5 = manufactured in the same manner as in Example 2 and then finely pulverized to obtain rubber powder, which was passed through a 250-mesh sieve to have an average particle size of 100 µm "glass fiber"; Asahi Fiber Glass Co., Ltd. Made, product name "Fiberglass""Vinylonfiber"; Kurare Co., product name "Claron""Aramidfiber"; Nippon Aramid Co., product name "Twaron"

A pressure of 15 is applied to each of the above molding materials by a compression molding method.
Resin foil 1 shown in FIG. 2 (longitudinal sectional view) and FIG. 3 (front view) after being cured at 0 kg / cm ² and a temperature of 155 ° C. for 5 minutes.
Was manufactured. The overall shape of this foil 1 is 55 mmφ ×
The thickness of each part (L1, L2 and L3 in FIG. 3) is 4 mm, and a bearing hole (hole diameter = foil inner diameter; 19.90 mmφ) 11 is provided in the center thereof. Further, when the presence state of the rubber particles in the peripheral portion of the bearing hole is visually observed, it is shown that the rubber particles 12 are concentrated toward the surface side, as shown in the longitudinal sectional view of FIG. It was This indicates that the rubber particles, which are foreign substances, migrated to the surface side during molding. Thereafter, the outer peripheral surface of the foil, which is bonded to the rubber portion, was subjected to a bonding pretreatment by buffing, and after degreasing and cleaning, an adhesive (manufactured by Road Far East Co .: trade name "Chemrock") was applied. Then, a compounded rubber composition for a tire comprising 50 parts of NR, 50 parts of BR, 100 parts of carbon black, 100 parts of process oil, 5 parts of zinc white, 1 part of stearic acid, 3 parts of sulfur and 0.5 part of a vulcanization accelerator, Using a predetermined mold, pressure 1
The rubber wheel shown in FIG. 4 was manufactured by vulcanization adhesion at 50 kg / cm ² and a temperature of 160 ° C. for 20 minutes. The outer diameter of this wheel is 75 mmφ.

Comparative Examples 1 to 5 Resin foils and rubber rings were produced in the same manner as in Example 1 using molding materials having the compositions shown in Table 2. The rubber particles used in Comparative Example 4 were produced by passing the EPDM rubber powder obtained by the same method as in Example 3 through a 80 mesh sieve. The rubber particles used in Comparative Example 5 were uncrosslinked SBR powder (manufactured by Japan Synthetic Rubber Co., Ltd., average particle diameter; 1).
00 μm). The rubber particles used in Comparative Example 6 are
Polyethylene powder (Mitsubishi Yuka Co., Ltd., average particle size: 200
μm). Further, in the table, the values marked with * are outside the scope of the present invention.

[0019]

[Table 2]

(2) Performance Evaluation With respect to the rubber wheels of each of the above examples and comparative examples, the rubber adhesion of the resin foil, the impact strength of the resin foil, and the fitting property of the bearing were evaluated. Rubber adhesion is JISK63
A 90 ° peel test according to 01 was used. Impact strength is J
It was based on the Charpy impact strength of ISK6911. Regarding the fitability of the bearing,
A needle bearing having an accuracy of 1/1000 obtained by cutting the outer diameter was actually press-fitted, and it was tested to what extent the tight fit amount could be press-fitted without damaging the resin foil. The results are shown in Tables 3 and 4. In the column of bearing fitting evaluation in these tables, bearings with different tight fits were press-fitted and the presence or absence of damage to the foil was confirmed.

[0021]

[Table 3]

[0022]

[Table 4]

(3) Effects of the Examples In each of Examples 1 to 7, excellent performance was shown. That is, as a result of the peeling test, the adhesive force between the rubber portion and the surface of the resin foil showed the destruction of the rubber material and showed excellent adhesiveness. The impact resistance of the resin foil shows a Charpy impact strength of 53 to 58 kgfcm / cm ² , and 35 kgfcm.
The value greatly exceeded / cm ² . Although the weight of the resin foil for 3 inches used in this test in FIG. 2 was only 85 g, the rubber wheel made from this foil had a lower limit impact force of 58.
It was found that even if an impact energy of 8 joules was applied, there was no damage, and it was lightweight and had high strength. Regarding the fitability of the bearing, even if the bearing was press-fit with a tight fit amount of 0.20 mm or more, the foil was not damaged. As a result,
The variation shown in FIG. 2 (bearing outer diameter φ20 mm ± 0.
All of the general industrial bearings having 1) can be fitted.

When the content of the reinforcing fiber was as small as 50 parts (Example 6), the impact strength was 36 kgfcm / cm ^2.
Therefore, it is included in the practical range. When the content of the reinforcing fiber was as large as 200 parts (Example 7), the impact strength was 65 kgfcm / cm ² , the elongation at break was 1.2%, and the interference fit amount was 0.20 mm. It has excellent fitting properties.

On the other hand, the following results were obtained for the rubber wheels of each comparative example. In Comparative Examples 1 and 2, the amount of rubber particles blended was small (or not included), so the amount of interference fit was 0.10 mm, and cracking occurred on the foil, and the bearing fitting property was poor. In Comparative Example 3, it was found that the impact strength was as low as 26 kgfcm / cm ² due to the large amount of rubber particles blended, and cracking easily occurred due to impact, and therefore it was unsuitable for use as an industrial rubber wheel. In addition, rubber particles were floating on the surface of the foil, and the appearance was poor. The impact strength of Comparative Example 4 is as low as 28 kgfcm / cm ² as in Comparative Example 3. It is considered that this is because the compounded rubber particles have a large diameter and the voids of the rubber particles themselves give a void effect to the resin.

In Comparative Example 5, since uncrosslinked rubber particles were used, the shape of the rubber particles was not retained in the molding material, and the rubber component itself migrated toward the surface during molding, but some heat was generated. The resin was in a state of being compatible with the curable resin, and the effect of adding the rubber particles was not sufficiently exhibited. Therefore, the foil was cracked when the interference fit amount was 0.15 mm. That is, the bearing fitting property was slightly inferior. The impact strength also showed a slightly low value (33 kgfcm / cm ² ). In Comparative Example 6, since polyethylene particles were blended in place of rubber particles, most of the polyethylene component floated out near the wheel surface during molding, and the polyethylene component was inactive in adhesion, resulting in interfacial peeling at the adhesion interface. It turned out that it cannot be used as a wheel for rubber wheels. Moreover, the impact strength was also slightly low, and there was no improvement in bearing fitability.

The present invention is not limited to the specific examples described above, but various modifications may be made within the scope of the present invention depending on the purpose and application. That is,
The rubber particles may be those obtained by physically pulverizing a crosslinked solid rubber or by subjecting the rubber to crosslinking and pulverization during polymerization of the rubber, and it is preferable that the apparent specific gravity is small.

[0028]

EFFECT OF THE INVENTION The foil of the present invention is made of resin, and since rubber particles are transferred to the surface side of the foil and concentrated, it is excellent in rust resistance and lightweight, and the outer diameter of the bearing can be easily varied. Can be absorbed into, and has excellent impact strength,
Further, it has excellent adhesiveness with the rubber portion formed on the outer peripheral side thereof. Therefore, the rubber wheel using this is very excellent in caster performance.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a state in which rubber particles are dispersed in a resin foil.

FIG. 2 is a vertical sectional view of a resin foil manufactured in an example.

FIG. 3 is a front view of the resin foil shown in FIG.

FIG. 4 is a vertical sectional view in which a part of a rubber wheel manufactured in an example is cut away.

FIG. 5 is an explanatory diagram showing a variation in outer diameter of a commonly used bearing.

[Explanation of symbols]

1; Resin foil, 11; Bearing hole, 12; Rubber particles, 2; Rubber part, 3; Bearing, 31; Shaft hole.

Claims (2)

[Claims] 1. A raw material containing 100 parts by weight of a liquid thermosetting resin, 5 to 20 parts by weight of crosslinked or partially crosslinked rubber particles having an average particle size of 200 μm or less, reinforcing fibers, an inorganic filler, a plasticizer and a crosslinking agent. A resin foil used for a rubber wheel for casters, which is manufactured by mixing, molding into a predetermined shape, and then curing, and having the rubber particles concentrated on the surface side. 2. A rubber wheel for casters, comprising the resin foil according to claim 1 and a rubber portion joined to a side peripheral surface of the resin foil via an adhesive layer.