JP2000289045A - Manufacture of weather strip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a weather strip made of a thermoplastic elastomer foam in which a shape is stabilized and a flaw gener ated by cutting and breakage in production is not caused. SOLUTION: The method for manufacturing the weather strip in which a hollow seal part and a fixed part are equipped and at least the hollow seal part is a foam of thermoplastic elastomer(TPE) having <=5 mm wall thickness, comprises a heating process for heating the TPE and melting it to obtain the molton TPE, a mixing process of a foaming agent in which the foaming agent is mixed with the molton TPE in pressurization to obtain a foamable composite, a foaming process in which the foamable composite is extruded in the atmosphere through an extrusion die 9 having a prescribed shape and a primary foam 11 is produced, a sizing process in which the primary foam 11 is passed through a movable pressure-welding sizing means 13 to stabilize the shape and a secondary foam 14 is produced, and a cooling process in which the secondary foam 14 is cooled and the weather strip 17 is produced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a weather strip used for preventing rainwater or the like from entering the inside of an opening / closing section of an automobile. A weatherstrip including a trunk seal used for a trunk portion, a cowl seal used for a bonnet portion, and the like,
The present invention relates to a method for manufacturing a weather strip for an automobile, which is made of a thermoplastic elastomer foam, has excellent shape stability, has no defects such as scratches, and does not cause cutting during manufacturing.

[0002]

2. Description of the Related Art A weather strip is fixed to a body side frame or a door frame as a movable member which constitutes an opening of a vehicle, and is elastically contacted with the other to seal a gap between the movable member and the fixed member. Exhibits the function as a member.

Conventionally, as a material for forming a weather strip for an automobile, a rubber material of a crosslinking reaction type such as polychloroprene rubber, ethylene propylene rubber (EPDM) or the like has been used. The solid portions provided as needed were both formed of crosslinked rubber.

A main member of the weather strip is an extruded portion formed into a continuous strip by extrusion. The extruded portion is cut in accordance with the size of a portion to be sealed of a member to be mounted, and molded as required. A part is provided, and the extruded part and the molded part are connected to be mounted.

[0005] However, it is difficult to reuse crosslinked rubber, and it is cut into chips and solidified with a binder to be used as sheets or blocks, or burned to produce a part of industrial waste except for burning. In addition, there was a need to switch to reusable materials from the viewpoint of reducing waste and protecting the environment.

[0006] As a reusable material, a thermoplastic elastomer has been studied as a weatherstrip material, and is already known in Japanese Patent Application Laid-Open No. Hei 7-246646.

[0007]

A weatherstrip made of a thermoplastic elastomer is also manufactured by extrusion. That is, a predetermined thermoplastic elastomer or a composition thereof is supplied to a hopper of an extruder, and is melted while being moved forward of the extruder by a screw in a cylinder to form a molten TPE, and a blowing agent is applied to the molten TPE under pressure. Injecting and kneading, the foaming composition in which the foaming agent is uniformly dispersed is extruded through a die having a predetermined shape and released to the atmospheric pressure, and the weather strip is formed by vaporizing the foaming agent to form a continuous strip-shaped thermoplastic elastomer foam. Manufactured.

In the production of such a weather strip made of a thermoplastic elastomer, when the foamed composition is extruded through a die and released to the atmospheric pressure to form a foam, a foaming agent is three-dimensionally formed in a molten state of the thermoplastic elastomer. Since the foamed composition rapidly expands into a foam, the shape of the resulting foam, particularly the cross-sectional shape, tends to be unstable. FIG. 3A shows an example of a weather strip having a normal cross-sectional shape, and FIGS. 3B and 3C show examples of a weather strip having a deformed cross-sectional shape. The deformed part is 1
Weather strips irregularly generated in the extruded portion of the book cause poor mounting and poor sealing, and have poor appearance and are not preferable.

In order to solve such shape instability, a method of providing a sizing die after an extrusion die is considered. As shown in FIG. 4, the sizing die has an inner surface shape along the cross-sectional outer shape of the weather strip to be extruded, and the primary foam extruded therein passes while sliding on the inner surface. It is intended to prevent deformation of the cross-sectional shape. The sizing die 23 illustrated in FIG. 4 includes an upper die 23a, two middle dies 23b, and a lower die 23c. The lower die 23c is fixed to a base, and the middle die is passed while passing the primary foam. It is used so as to cover 23b and the upper die 23a.

However, the sealing portion of the weatherstrip is usually hollow with a thickness of 5 mm or less, generally about 0.5 to 3 mm, and the thermoplastic elastomer immediately after foaming is compared with a crosslinked rubber foam. The strength is low, especially when the thin-walled foam is passed through the sizing die as described above while sliding, as described above, even if the taper is provided so as to have a small diameter at the end of the extrusion direction, even if the resistance at the time of passing is reduced. ,
Cutting or partial breakage of the weather strip occurs.

An object of the present invention is to have a stable shape, and to prevent scratches due to cutting or breakage during manufacturing.
An object of the present invention is to provide a method for producing a weatherstrip made of a thermoplastic elastomer foam.

[0012]

SUMMARY OF THE INVENTION The present invention provides a method for manufacturing a weatherstrip having a hollow seal portion and a fixing portion, wherein at least the hollow seal portion is a foam of a thermoplastic elastomer (TPE) having a thickness of 5 mm or less. A heating step of heating and melting the thermoplastic elastomer to form a molten TPE, a foaming agent mixing step of mixing a blowing agent under pressure into the molten TPE to form a foamed composition, A foaming step of extruding into a primary foam through a shape die into atmospheric pressure, a sizing step of passing the primary foam through a movable press sizing means to form a secondary foam,
And a cooling step of cooling the secondary foam to form a weatherstrip.

[0013] By providing a sizing step of passing through the movable press sizing means to form a secondary foam, the foam is formed of a thermoplastic elastomer foam having excellent shape stability without being damaged by cutting or breakage during manufacturing. A weatherstrip is obtained.

The movable pressure contact sizing means is contacted with the primary foam as the primary foam moves, and the contact surface does not slide or damages or cuts the surface of the primary foam. Means to prevent deformation while moving with a slight sliding that does not cause the deformation. In order to stabilize the shape, it is preferable to hold the primary foam, and it is preferable that the movable pressure contact sizing means is constituted by two or more pressure contact members.

The thermoplastic elastomer may be a single-component thermoplastic elastomer or a composition containing a plurality of components. The final density of the foam constituting the weather strip is usually 0.4 to 0.7 g / cm ³ , and the maximum thickness in the cross-sectional shape is 5 mm or less. If the density is less than 0.4, the strength of the foam is too low,
If it exceeds 0.7, the flexibility is lowered and the sealing performance becomes insufficient, and both are not preferred.

The weatherstrip is preferably provided with a hollow seal portion in order to obtain sufficient sealing properties, and the thickness of the hollow seal portion is 5 mm or less. When the wall thickness exceeds 5 mm, the density of the foam is reduced to 0.4.
Even with g / cm ³ , the reaction force at the time of sealing becomes too large, and for example, if the part to be used is a door, there arises a problem that door tightness is deteriorated.

In the present invention, the thermoplastic elastomer comprises a crystalline polyolefin and a rubber material, wherein the weight ratio of the crystalline polyolefin / rubber material is from 10/90 to 90/90.
It is preferable that they are mixed in the range of 10.

Even when water is used as the main foaming agent, it can be uniformly dispersed, and it is possible to obtain a foam having the physical properties required for a weather strip and having a uniform cell diameter.

The crystalline polyolefin gives the foamed sealing member of the present invention physical properties such as high tensile strength, and the rubber material gives flexibility. Crystalline polyolefin /
When the weight ratio of the rubber material is less than 10/90, that is, when the ratio of the crystalline polyolefin is too small, the physical strength becomes insufficient, and when it exceeds 90/10, that is, when the rubber material is too small, the flexibility is sufficiently exhibited. Will not be.

The above weight ratio is preferably in the range of 15/85 to 45/55, that is, the range in which the rubber material component is large is more preferable in terms of flexibility and flexibility.

It is preferable that the movable pressure contact sizing means is a sizing roller because the structure is simple and there is no resistance to the passage and shape adjustment of the primary foam.

The movable press sizing means is not particularly limited as long as it is made of a material which does not deform or deteriorate due to contact with the thermoplastic elastomer in a molten state. It is preferable that the contact portion is made of polytetrafluoroethylene or a material containing polytetrafluoroethylene. It is a material with excellent heat resistance and lubricity. It does not deform or deteriorate even when it comes into contact with the thermoplastic elastomer in the molten state, and it is stable without damaging the surface of the primary foam because it does not stick. It can be a secondary foam maintaining the shape.

[0023]

FIG. 1 shows an example of an apparatus used in the present invention.
It was shown to. The apparatus shown in FIG. 1 includes an extruder 1 having a foaming agent supply device 7 and an extrusion die 9, a movable pressure contact sizing means 13, and a cooling water supply device. It is preferable that the foaming agent supply device is provided with a foaming agent storage tank and a constant-quantity supply unit.

An example of a method for manufacturing a weatherstrip using the apparatus illustrated in FIG. 1 is as follows. The thermoplastic elastomer is supplied to the hopper 3 of the extruder 1,
The extruder 1 is fed to the front extrusion die 9 side by the rotation of a screw provided in the cylinder. The thermoplastic elastomer is heated and melted in the cylinder 5,
In the molten state, a blowing agent is added from the blowing agent supply device 7 under pressure and mixed to form a foamed composition.

The foaming composition is released from the extrusion die 9 under atmospheric pressure, and the foaming agent is vaporized to form the primary foam 1.
1 is formed. The primary foam is easily deformed because it is close to the melting point or the flowing temperature of the thermoplastic elastomer.

The primary foam 11 is made into a secondary foam 14 by stabilizing the shape by the movable pressure contact sizing means 13 and is cooled by spraying cooling water by a cooling water supply device 15 which is a preferred example of the cooling means. Thus, a weather strip 17 as a final product is formed. Weatherstrip 17
Is generally cut to a predetermined length by a cutting device provided immediately after this step.

FIG. 2 shows an example in which the sizing rollers 20a, 20b and 21 are used to manufacture the weather strip 17 having a substantially cylindrical seal portion as a preferred example of the movable pressure contact sizing means 13. The primary foam 11 extruded from the extrusion die 9 has a shape 2 along the outer shape of the cylindrical portion of the weather strip 17.
From left and right with the individual sizing rollers 20a, 20b,
Further, the sizing roller 21 having a shape along the flat fixing portion is nipped and pressed from the bottom surface, thereby stabilizing the shape.

The installation position of the movable pressure welding sizing means 13 is set in consideration of the characteristics such as the melting point of the thermoplastic elastomer used, the shape and thickness of the weather strip, the extrusion speed, and the like. It is particularly preferable that the temperature be at a temperature at which the bubbles start to solidify. Specifically, when a mixture of crystalline polyolefin and a rubber material is used to produce a foam having a density of 0.4 to 0.7, the distance from the extrusion die (L in FIG. 2) is 15 to 15. It is preferably in the range of 40 mm. When this thermoplastic elastomer is used, the material temperature immediately after being extruded from the extrusion die is 180 to 200.
℃, but when it reaches the sizing roller,
It is preferably about 160 to 180 ° C and 5 to 25 ° C lower than immediately after extrusion.

Examples of the movable press-contact sizing means 13 include a sizing roller, a conveyer belt having a predetermined press-contact surface shape, a caterpillar-shaped sizing means formed by connecting dies, and the like.

In the present invention, as the suitable thermoplastic elastomer used as the weatherstrip material, known thermoplastic elastomers can be used without particular limitation.
Specific examples include polyester elastomers, styrene / butadiene copolymer elastomers, polyurethane elastomers, and polyolefin elastomers. Among the above-mentioned thermoplastic elastomers, it is preferable to use a thermoplastic elastomer in which a crystalline polyolefin and a rubber material are mixed. Raw materials suitable as raw materials for such a thermoplastic elastomer are as follows.

(1) Crystalline Polyolefin The above-mentioned crystalline polyolefin is a homopolymer of an α-olefin having 1 to 4 carbon atoms or a copolymer of two or more monomers. The α-olefin having 1 to 4 carbon atoms is appropriately selected from ethylene, propylene, 1-butene and isobutene.

(2) Rubber Material Examples of the rubber material include the following, which can be used without any particular limitation. -Diene rubber: nitrile rubber (NBR), styrene butadiene rubber (SBR), isoprene rubber (IR), chloroprene rubber (CR), ethylene propylene diene rubber (EPDM), natural rubber (NR), and the like.

Olefin rubber: ethylene propylene rubber (EPR), butyl rubber (IIR) and the like.

Halogenated butyl rubber such as brominated butyl rubber (Br-IIR).

Other polyurethane rubber, acrylic rubber, fluorine rubber, silicone rubber, chlorosulfonated polyethylene, etc.

The rubber materials exemplified above can be used alone or
More than one species are used in a mixture.

In particular, IIR, EPDM, EPR, NBR,
Use of one or more selected from Br-IIR, NR is preferred.

The crystalline polyolefin and the rubber material may be homogeneously compatible with each other, but it is also a preferred embodiment that one of the crystalline polyolefin and the rubber material has a so-called "sea / island" structure in which one of the particles is dispersed in fine particles. In particular, it is preferable that the rubber material is an island.

It is also a preferred embodiment to add and mix various additives to the rubber material as necessary. Examples of such additives include antioxidants, waxes, coloring agents, fillers, softeners such as plasticizers and process oils, and tackifiers.

The following are examples of the above-mentioned filler. Powders: metal powders such as aluminum powder, silica sand, hard clay, talc, calcium carbonate, titanium oxide, silica, calcium sulfate, calcium carbonate, inorganic powders such as aluminum hydroxide, and organic powders such as starch and polystyrene powder.

Short fibers: whiskers such as glass fibers (milled fibers), carbon fibers, aramid fibers, and potassium titanate whiskers.

Others: carbon black, mica, etc.

The above-mentioned fillers are used alone or in combination of two or more. In a preferred embodiment, these fillers may be subjected to a surface treatment such as a primer treatment and various kinds of coupling agent treatments if necessary.

As a softening agent, dioctyl phthalate (DO)
P), plasticizers such as dicarboxylic acid esters such as dioctyl sebacate (DOS) and phosphate esters, and process oils classified as aromatic oils, naphthenic oils, and paraffinic oils. You. Of these softeners, the plasticizer is mainly N
It is used as a softening agent for highly polar rubber materials such as BR and polyurethane rubber, and process oil is mainly used for natural rubber and EPDM, but is not particularly limited. I don't care.

The above-mentioned fillers, softeners and the like are selected according to the characteristics required for the foamed sealing member as a product, and the amount of addition is also adjusted.

In the rubber composition described above, the cross-linking agent used for finely cross-linking the rubber material may be any cross-linking agent generally used for cross-linking rubber.

In the sulfur crosslinking, sulfur and a vulcanization accelerator are used, and in the peroxide crosslinking, organic peroxides such as dicumyl peroxide, MEK peroxide and benzoyl peroxide are used. Oxime compounds such as phenolic resins and benzoquinone oximes are used for IIR, and metal oxides such as zinc oxide and magnesium oxide, thiourea and the like are used for CR and the like.

In addition to the above-mentioned crosslinking method, it is also possible to perform crosslinking using radiation such as an electron beam.

Water is suitable as the foaming agent, but other foaming agents can be used in combination. Such a foaming agent is an organic compound such as a liquid hydrocarbon, a liquid ketone compound, or a hydrogenated chlorofluorocarbon, which forms a foam by vaporization, or decomposes like sodium hydrogen carbonate to generate a gas. And the like to form a foam.

Examples of the material containing polytetrafluoroethylene which is a member pressed against the primary foam used in the sizing step include a metal or a member having high heat-resistant resin coated with polytetrafluoroethylene. A member in which a metal and polytetrafluoroethylene are plated and coated on a metal surface is exemplified.

[Brief description of the drawings]

FIG. 1 is a schematic view showing equipment used for a method of manufacturing a weather strip according to the present invention, provided with a movable pressure welding sizing means.

FIG. 2 is a diagram showing an example in which three sizing rollers are used as sizing means for movable pressure welding;

FIG. 3 is a diagram showing an example of a normal cross section and a deformed cross section of a weather strip formed without using a movable pressure welding sizing means.

FIG. 4 shows an example of a sizing die.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Extruder 9 Extrusion die 11 Primary foam 13 Movable pressure contact sizing means 14 Secondary foam 17 Weather strip

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yoshiyuki Gozozo 1-17-18 Edobori, Nishi-ku, Osaka-shi, Osaka F-term (reference) 4F207 AA03 AA09 AA45 AA47 AG20 AH23 AJ03 KA01 KA11 KF04 KK01 KK76 KW23 KW26 4F212 AA03 AA09 AA45 AA47 AG20 AH23 AJ03 UA09 UB02 UG03 UG07 UN13

Claims (4)

[Claims] 1. A method for producing a weather strip, comprising a hollow seal portion and a fixed portion, wherein at least the hollow seal portion is a foam of a thermoplastic elastomer (TPE) having a thickness of 5 mm or less, wherein the thermoplastic elastomer TPE by heating and melting
A heating step, a foaming agent mixing step of mixing a foaming agent under pressure into the molten TPE to form a foamed composition, and extruding the foamed composition to atmospheric pressure through a die having a predetermined shape to obtain a foamed composition.
A foaming step of forming a secondary foam, a sizing step of passing the primary foam through a movable press sizing means to form a secondary foam, and a cooling step of cooling the secondary foam to form a weatherstrip. Method of manufacturing weatherstrips. 2. The thermoplastic elastomer according to claim 1, wherein the crystalline polyolefin and the rubber material are mixed in a weight ratio of the crystalline polyolefin / rubber material of 10/90 to 90/10. A method for producing the weatherstrip according to the above. 3. The method for manufacturing a weather strip according to claim 1, wherein the movable press sizing means is a sizing roller. 4. The movable press sizing means wherein at least a contact portion with the primary foam is made of polytetrafluoroethylene or a material containing polytetrafluoroethylene. The method for producing a weatherstrip according to any one of the above.