JPH0633031A - Adhesive and laminated pipe applied with the same - Google Patents

Abstract

PURPOSE:To obtain a high-performance laminated pipe made up of a fluororesin and rubber by application of an adhesive having stable and high adhesiveness in e.g. covering the surface of a fluororesin with a rubber through extrusion. CONSTITUTION:This adhesive can be obtained by incorporating an organosiloxane-based adhesive main agent with a silane coupling agent and pulverized silica. By applying this adhesive for bonding between a fluororesin and a rubber, the flow on the surface of the resin during the extrusion of the rubber and the debonding of the rubber off the resin surface in the cure shrinkage of the rubber can be prevented. And, a fluororesin inner pipe 2 and a rubber outer pipe 4 are mutually laminated through an adhesive layer 3 consisting of this adhesive, and the resulting laminate is monolithically bonded through curing, thus obtaining the objective laminated pipe 1 with low volatile matter permeability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive agent for a fluororesin and rubber, and further to a laminated pipe made of the fluororesin and rubber obtained by using the adhesive agent.

[0002]

2. Description of the Related Art Recently, it has been important to reduce the amount of volatile substances that permeate through a hose or the like due to various environmental regulations. As for the hose used for gasoline as an example of the volatile substance, a fluororubber having low gasoline permeability may be used as a thick wall, but the fluororubber has a high specific gravity of 1.8 to 1.9. Moreover, since it is expensive, it is difficult to put it into practical use.

Therefore, as described in Japanese Utility Model Publication No. 57-38272, a hose having a thin-walled fluororesin inner tube covered with a thick-walled rubber outer tube has been considered. The surface of the thin inner tube made of fluororesin is treated with metallic sodium or corona discharge, and the thick outer tube made of rubber is attached to the inner tube through the organosiloxane adhesive. In order to obtain a hose suitable for the above-mentioned purpose by integrally vulcanizing these two tubes, a technique has been proposed.

[0004]

However, according to the conventional technique as exemplified in the above-mentioned Japanese Utility Model Publication No. 57-38272, the rubber outer tube is treated with the adhesive after the corona discharge treatment of the fluororesin. However, if the rubber outer tube material contains a high-viscosity oil-resistant compound or a resin for improving adhesiveness, the rubber outer tube is There is a problem that the adhesive is washed off by pressure.

Further, there is also a problem that the adhesive strength is reduced by the peeling of the adhesive from the surface of the fluororesin due to the contraction during vulcanization when the hose is completed.

As a countermeasure against these problems, even if the adhesive is applied to cure the adhesive by heat treatment, a heat treatment line of several tens of meters is required for the heat treatment, which avoids an increase in manufacturing cost. I can't.

In view of the above, according to the present invention, after the adhesive is applied to the surface of the fluororesin inner pipe, it is washed away when the rubber outer pipe is covered by the extrusion process, or when the hose is vulcanized. To provide an adhesive between a fluororesin and a rubber that does not separate from the fluororesin inner tube due to shrinkage of the fluororesin, and a laminated pipe comprising a fluororesin and a rubber having stable properties by using the adhesive. The purpose is to

[0008]

In order to achieve the above-mentioned object, the invention of claim 1 is such that the composition of the adhesive comprises a silicon-based adhesive main agent, an organic silane coupling agent, and an inorganic fine powder. Silica is not added, and by increasing the adhesive strength of the adhesive by the function of each of the above additives and improving the adhesive strength of the adhesive on the fluororesin surface,
It prevents the adhesive from being removed from the surface of the fluororesin during rubber extrusion and vulcanization.

Specifically, the means for solving the problems of the invention of claim 1 is an adhesive for adhering a fluororesin and rubber,
At least one of 0.01 to 10 parts by weight of a silane coupling agent and 1 to 35 parts by weight of finely divided silica is mixed with 100 parts by weight of the organic siloxane-based adhesive main agent.

Further, the invention of claim 2 uses the adhesive of the fluororesin and rubber according to the invention of claim 1 so that the silane coupling agent and the fine powder are blended in the adhesive main agent. The behavior of silica prevents the flow of the adhesive when the rubber outer tube is coated on the surface of the fluororesin inner tube by extrusion and the peeling of the adhesive due to the contraction during vulcanization. It is intended to obtain a laminated tube in which resin and rubber are strongly bonded.

Specifically, the means for solving the problems of the second aspect of the present invention is to provide a fluororesin inner tube whose outer peripheral surface is corona-discharge treated so as to have a wetting index of 38 to 60 dyne / cm, and the fluororesin inner tube. A rubber outer tube that is provided on the tube via the adhesive layer made of the adhesive according to claim 1 and covers the fluororesin inner tube, and the fluororesin inner tube is provided with the rubber outer tube. The rubber outer tube is integrally vulcanized and bonded via an adhesive layer.

The present inventor has studied the adhesiveness between the fluororesin and the rubber in a hose of low permeability such as gasoline as described above. As a result, the fluororesin and the rubber are vulcanized and adhered to each other during the lamination molding by pressing. Even if it is an adhesive that can be used, when it is applied to lamination molding by extrusion of rubber, the flow of the above adhesive is seen and it is necessary on the surface of the fluororesin due to insufficient pressure per unit area. The phenomenon in which a sufficient adhesive force cannot be obtained has occurred, and all of these phenomena occur based on the magnitude of the cohesive force of the adhesive and the adhesion mechanism between the fluororesin and the adhesive. It was confirmed.

Therefore, as a result of earnestly researching the improvement of the adhesiveness between the fluororesin and the adhesive, a silicone-based adhesive as the adhesive used for adhering the fluororesin and the rubber to the silane coupling agent (organic substance). ) Or silica (inorganic substance) is used, the cohesive force of the adhesive is improved by the coupling reaction in the adhesive, or the anchor effect of the adhesive on the fluororesin surface is produced. Therefore, the flow of the adhesive at the time of lamination molding by extrusion of the rubber and the peeling of the adhesive at the time of shrinkage at the time of vulcanization due to the insufficient adhesive force are suppressed, and the adhesive force between the fluororesin and the rubber is improved. We obtained the knowledge that

The invention of claim 1 and the invention of claim 2 are based on this finding, and an adhesive obtained by adding a silane coupling agent and silica to the adhesive main agent in each of the above inventions. The action of is brought about by each function as described below.

That is, the silane coupling agent has a function of increasing the speed of the crosslinking reaction of the silicon-based adhesive main agent such as organic siloxane and increasing the viscosity of the adhesive itself.

[0016] Regarding silica, finely divided ones inherently have a thickening action, and further exhibit an anchoring effect between the adhesive molecule and the adhesive interface, so that the adhesive is separated from the fluororesin surface. Disappear. Silica also has a function of reinforcing the adhesive.

A well-known organic siloxane adhesive is preferably used as the adhesive main agent in the adhesive between the fluororesin and the rubber.

The silane coupling agent to be added to the above-mentioned adhesive main agent is N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ.
Aminosilane adhesives such as -aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane and N-phenyl-γ-aminopropyltrimethoxysilane are preferably used.

The amount of the above aminosilane-based adhesive compounded with respect to the above-mentioned adhesive main agent is such that the main agent stock solution (solid content: 5.9 to 7.1).
%) 0.01 to 10 parts by weight with respect to 100 parts by weight. As the blending amount increases, the viscosity of the adhesive main agent increases and the coating strength of the adhesive increases, but when it exceeds 10 parts by weight, the adhesive gels and a curing phenomenon is observed. Also,
If it is less than 0.01 part by weight, the above-mentioned action due to the compounding does not occur. Therefore, the preferable range of the compounding amount is 0.1 to 8 parts by weight.

Further, as the silica to be blended in the adhesive main agent, finely powdered silica is preferable, and the finely powdered silica is silicic acid anhydride, hydrous silicic acid, synthetic silicate or the like. A fine silica powder having a particle diameter of 0.01 to 40 μm is used.
As the particle size becomes smaller, the dispersibility in the adhesive main agent becomes better, but the apparent specific gravity becomes small and the particles tend to scatter and the handleability deteriorates. The larger the particle size, the more difficult it is to scatter and the better the handleability. However, if the particle size exceeds 40 μm, the dispersibility in the adhesive base compound deteriorates and the silica particles settle out. There is a concern that silica will come off. Accordingly, the particle size range of the finely divided silica is preferably 0.02 to 30 μm.

The amount of the finely powdered silica blended with the adhesive main agent is such that the main agent stock solution (solid content: 5.9 to 7.1%).
It is 1 to 35 parts by weight with respect to 100 parts by weight. As the blending amount increases, the viscosity of the adhesive main agent increases and the coating film strength of the adhesive increases, but if it exceeds 35 parts by weight, the viscosity of the undiluted adhesive solution becomes excessive and sedimentation of finely powdered silica occurs, further adhering. This may lead to a decrease in the crosslinking rate of the main agent. Also, 1
If it is less than part by weight, the above function due to the composition is not observed. Therefore, the preferable range of the compounding amount is 3 to 30 parts by weight.

Next, as the fluororesin to which the adhesive according to the first aspect of the invention is applied and which is used for the inner tube of the laminated tube according to the second aspect of the invention, a part of hydrogen in the carbon chain is used. Remain without being replaced by fluorine, for example, polyvinylidene fluoride resin (PVDF), polyvinyl fluoride resin (PVF), ethylene / tetrafluoroethylene copolymer resin (ETFE), ethylene / chlorotrifluoroethylene copolymer (ECTFE) Etc. can be used. In addition to the above fluororesins, for example, polytetrafluoroethylene / hexafluoropropylene copolymer resin (FEP) in which the hydrogen is completely replaced by fluorine and halogen elements, tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer resin, Polychlorotrifluoroethylene resin and the like can also be used.

When each of the above-mentioned fluororesins is formed on the outer peripheral surface of the mandrel by extrusion, the wetting index on the surface of each fluororesin is usually 30.
It is less than or equal to dyne / cm. When the wettability of the fluororesin surface is 30 dyne / cm or less, the activity of the fluororesin surface with respect to the adhesive is low. Therefore, the wettability index of the surface is increased to improve the wettability. It is advantageous to have an adhesive force.

The wettability is improved by subjecting the surface of the fluororesin to corona discharge treatment so that the wettability index is 38 to 70.
The range may be dyne / cm. However, in order to make the wetting index above 70 dyne / cm, not only a high-power corona discharge device is required or the above treatment requires a long time. Since there is a concern that it will cause curing,
Corona discharge treatment on the surface of fluororesin has a wetting index of 3
It is preferably applied in the range of 8 to 60 dyne / cm.

[0025]

Embodiments of the present invention will be described below with reference to the drawings.

(Example I) In order to obtain an adhesive composition of a fluororesin and rubber, in order to obtain a constitution in which each component of an organic silane coupling agent and an inorganic fine powdery silica is blended with a silicon-based adhesive main agent. , As shown in Table 1, adhesive main agent,
A silane coupling agent and finely divided silica were each added, and the No. Adhesives 1 to 11 were prepared respectively. In addition, the case where the composition is out of the scope of claim 1 of the present invention is No. 1 of the comparative example. It was prepared as 1 to 6 and is also shown in Table 1.

Specifically, an organic siloxane-based adhesive which is a condensate having a siloxane bond as a silicon-based adhesive agent (trade name, Chemlok 607: LOARD Hughson Chem
icals) is used as the main adhesive agent and the silane coupling agent is an aminosilane adhesive, γ-aminopropyltriethoxysilane (trade name, KBE90).
3: Shin-Etsu Chemical Co., Ltd.) was used. The finely divided silica is white carbon having a particle size of 0.022 μm (trade name, Hi-Sil 233: manufactured by PPG Industries).
It was used. In addition, among the composition of the adhesive composition shown in Table 1, No. of the example. The fine powdery silica in 3 and 4 had a particle size of 16 μm (trade name, Nipseal VN3: manufactured by Nippon Silica Co., Ltd.) and was used as a comparative example. The finely divided silica in 4 had a particle size of 50 μm (trade name, Mistron Vapor: manufactured by Nippon Mistron Co., Ltd.).

No. 1 of the embodiment according to the invention of claim 1 obtained by each of the above-mentioned formulations. The state of the adhesive between the fluororesin and the rubber in Nos. 1 to 11 is that the silane coupling agent containing the above components and / or the fine powdery silica containing the above properties are well dispersed in the adhesive main component containing the above components. A good initial state of the adhesive was obtained.

On the other hand, Comparative Example No. 1 in which the silane coupling agent was excessively mixed. The adhesive of No. 3 aggregated and gelled. In addition, No. of the comparative example in which the particle size of the finely divided silica to be blended is excessively large. No. 4 of the comparative example in which the adhesive and the finely divided silica are excessively mixed. In all of the adhesives of No. 5, silica precipitation was observed.

Next, in No. Nos. 1 to 11 and Nos. The adhesive strength of each of the adhesives 1 to 6 was tested as follows.

Ethylene / tetrafluoroethylene copolymer resin (ETFE) widely used as fluororesin
A fluororesin inner tube having a wall thickness of 0.5 mm was prepared using a composition containing as a main ingredient, and further treated by corona discharge treatment so that the surface wetting index became 44 (No. Only those corresponding to .10 were processed to have a wetting index of 60).

On the surface of each of the treated fluororesin inner tubes, No. Nos. 1 to 11 and Nos. 1 to
After applying each of the adhesives of No. 6 to Table 1 on each application surface
No. 1 of the example by further providing a rubber outer tube made of a rubber type shown in FIG. 1
No. 11 to No. 11 of the comparative example. Each laminated tube was prepared by applying each of the adhesives 1 to 6.

For each of the above laminated tubes, a sample for measuring the peeling load was cut by cutting it to a length of 1 inch, reaching the surface of the fluororesin inner tube, and providing cuts parallel to the axis of the inner tube and in the radial direction. The sample was prepared and the peeling load was measured for each of these samples. The results are also shown in Table 1.

[0034]

[Table 1]

According to the results shown in Table 1, No. 1 in Example I according to the present invention. Nos. 1 to 11 of Comparative Examples corresponding to the conventional examples in which the silane coupling agent and the fine powdery silica were not mixed were used. Compared with No. 1, the peeling load is remarkably improved. As a result, the adhesive between the fluororesin and the rubber according to the present invention does not flow due to the rubber extrusion process on the coating surface and does not peel off from the coating surface due to contraction during vulcanization, and thus has excellent adhesive strength. It can be seen that

Incidentally, in Comparative Example No. The adhesive of No. 2 shows excellent adhesive strength at 125 ° C. after application of the adhesive.
This is because the heat treatment for 5 minutes was added. From this example, it is clear that the adhesive according to the present invention can obtain an excellent adhesive force without heat treatment after applying the adhesive.

Further, in Comparative Example No. 1 in which the silane coupling agent was excessively mixed with the adhesive main agent. No. 3 of the comparative example in which the particle size of the finely divided silica is excessively large. No. 4 of the comparative example in which the finely divided silica is excessively mixed. No. 5 of the comparative example showing the situation when applied to the fluororesin surface having poor wettability.
In No. 6, no sufficient peeling load was obtained and the adhesive strength was not good.

(Example II) This example II is a laminated tube made of a fluororesin and rubber to which the adhesive according to the present invention obtained in the above example I is applied.

As shown schematically in FIG. 1, in a laminated pipe 1 according to Example II of the present invention, a rubber outer pipe 4 is extruded on an outer peripheral surface of a fluororesin inner pipe 2 via an adhesive layer 3. It is provided by processing. And the rubber outer tube 4
A reinforcing system layer 5 formed by braiding polyester fibers or the like is provided on the outer peripheral surface of the, and the outermost layer is covered with an outer rubber 6.

Hereinafter, the laminated pipe 1 will be described in detail with reference to the process chart shown in FIG.

In this Example II, the molten fluororesin is extruded onto the mandrel 11 made of TPX resin by using the crosshead type resin extruding device 10 to form the fluororesin inner pipe 2 as the innermost resin pipe. Form. The wall thickness of this fluororesin inner tube 2 is 0.1 to 0.5 mm. Fluororesin was used in Example I for testing E
Needless to say, the above-mentioned various fluororesins including TFE can be appropriately used.

The wetting index of the surface of the fluororesin product molded by extrusion is usually 30 dyn as described above.
Since it is less than e / cm, the fluororesin inner tube 2 is also guided to the corona discharge treatment device 12 with the mandrel 11 still inserted, and the outer peripheral surface is subjected to corona discharge treatment. As the corona discharge treatment device 12, a gate type electrode is used in this embodiment II, but a ball type electrode or the like can also be used.

In this case, the phenomenon that the surface of the adherend is modified and activated by corona discharge has not been clarified by physical and chemical theory, and further the surface is modified by the material of the fluororesin used. Because the degree of
The frequency of the generator in the device (20-25KH
z), voltage (8 to 70 KV), etc.
It is set so that a wetting index of 0 dyne / cm is obtained.

Then, the fluororesin inner tube 2 whose surface wetting index is treated by the corona discharge treatment within the above target range is immersed in the adhesive agent tank 13 so that the surface of the inner tube 2 is coated with the adhesive according to the present invention. The adhesive layer 3 is formed. In particular, when the adhesive agent is one in which finely powdered silica is mixed with the main adhesive agent, the adhesive agent tank 1
3 is equipped with a stirrer and is preferably capable of homogenizing the adhesive. In FIG. 2, reference numeral 14 is a feeding roller.

When the adhesive is a mixture of the main adhesive agent and a silane coupling agent such as an aminosilane adhesive, the roller coating is carried out without using the dipping method using the adhesive tank 13. Alternatively, a coating means such as

The adhesive layer 3 formed on the surface of the fluororesin inner tube 2 reaches the rubber extrusion device 16 after being dried while passing through the drying device 15.

In the rubber extruding device 16, the outer rubber tube 4 is formed on the outer peripheral surface of the adhesive layer 3 by extrusion. The rubber type applied to the rubber outer tube 4 is epichlorohydrin / ethylene oxide copolymer rubber (CHC),
Acrylonitrile butadiene rubber (NBR), hydrogenated N
BR (H-NBR), acrylic rubber (AR), etc.,
It is preferably used according to the composition as shown in Table 2.

[0048]

[Table 2]

In Table 2 above, the adhesion improver a is a phenolic resin such as a resol type phenol formaldehyde resin having a softening point of 65 ° C., and the adhesion improver b is an epoxy resin such as a bisphenol A type epoxy resin. The sex improving agent C is a thiourea compound, for example, 1,3
-Bis (dimethylaminopropyl) -2-thiourea, which is preferably added alone or in combination within the range of 1 to 10 parts by weight.

If the amount of the above-mentioned adhesion improver added is less than 1 part by weight, no action contributing to the adhesiveness of the rubber is recognized. Also, as the amount added increases, the adhesiveness improves, but
If the amount exceeds 0 parts by weight, tackiness occurs and the kneading of the rubber compounded product is hindered. Therefore, addition of 2 to 8 parts by weight is preferable.

The vulcanizing agent a is sulfur and the vulcanizing agent b is zinc dimethyldithiocarbamate.

The accelerator a is tetraethylthiuram.
It is a disulfide and the accelerator b is dibenzothiazyl disulfide.

Then, a polyester fiber or the like is knitted on the outer peripheral surface of the rubber outer tube 4 by a reinforcing braiding device 17 to form a reinforcing system layer 5, and the outer rubber coating device 18 is provided on the outer peripheral surface of the reinforcing system layer 5. The outer rubber 6 is formed by coating.

The rubber composition used for forming the outer rubber 4 may be used as the rubber type used for forming the outer rubber 6. Besides, chlorosulfonated polyethylene rubber (CSM), chloroprene rubber and the like can be used.

As described above, a laminated pipe material obtained by sequentially laminating the fluororesin inner pipe 2, the adhesive layer 3 and the rubber outer pipe 4, and further coating the reinforcing system layer 5 and the outer rubber 6 Is vulcanized by steam vulcanization or hot air vulcanization to complete the laminated tube 1 according to the present invention.

When steam vulcanization is performed, the vulcanization operation 19 is performed and then the mandrel removal operation 20 is performed. The pre-vulcanization step and the mandrel removal operation 20 are performed, and then the vulcanization operation 19 is performed. The laminated tube 1 can be obtained by any of the mandrel removal pre-setting steps.

[0057]

As described above, according to the adhesive of the invention of claim 1, at least one of the silane coupling agent and the finely divided silica is blended with the organosiloxane-based adhesive main agent. Therefore, the flow of the adhesive at the time of the rubber extrusion process on the surface of the fluororesin and the peeling at the time of vulcanization shrinkage are prevented, so that the adhesive force between the fluororesin and the rubber is improved and stable adhesiveness is obtained.

Further, since the adhesive does not separate from the surface of the fluororesin without heat treatment, the improvement of the adhesive strength can be easily achieved.

According to the laminated pipe of the invention of claim 2, the inner pipe made of fluororesin whose outer peripheral surface is subjected to corona discharge treatment is made of rubber through the adhesive layer made of the adhesive according to the invention of claim 1. Since the outer tube is covered and integrally vulcanized and bonded, the fluororesin inner tube and the rubber outer tube are strongly bonded together, so the laminated tube has low permeability to volatile substances. It can be obtained as a tough and high performance hose.

Further, since the adhesive property of the adhesive is improved, a sufficient adhesive force can be obtained even when a rubber having a high Mooney viscosity or a high tackiness is used, so that a product adapted to any application can be manufactured. .

[Brief description of drawings]

FIG. 1 is a perspective view illustrating a laminated pipe made of fluororesin and rubber according to Example II of the present invention.

FIG. 2 is a process drawing of Example II described above.

[Explanation of symbols]

 1 Laminated Tube 2 Fluororesin Inner Tube 3 Adhesive Layer 4 Rubber Outer Tube 5 Reinforcement Layer 6 Outer Rubber

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location B32B 27/16 6122-4F 27/30 D 8115-4F

Claims (2)

[Claims] 1. An adhesive for adhering a fluororesin and rubber, wherein 0.01 to 10 parts by weight of a silane coupling agent and 1 to 35 parts by weight of finely divided silica are added to 100 parts by weight of an organic siloxane-based adhesive main agent. At least one of the above is compounded, and an adhesive characterized by the above-mentioned. 2. A fluororesin inner tube whose outer peripheral surface is subjected to corona discharge treatment so as to have a wettability index of 38 to 60 dyne / cm, and an adhesive comprising the fluororesin inner tube comprising the adhesive according to claim 1. And a rubber outer tube provided by covering the fluororesin inner tube, the rubber outer tube being integrated with the fluororesin inner tube via the adhesive layer. A laminated pipe characterized by being vulcanized and adhered.