JP2002138166A - Rubber mixture and method of producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber mixture obtained by kneading a rubber component (1) and a non-rubber component (2) comprising an organic component, wherein the dispersion of component (2) is good and the rubber component (1) has the desired molecular weight, and to provide a molded sheet and a laminate using the rubber mixture. SOLUTION: This rubber mixture obtained by kneading a rubber component (1) and a non-rubber component (2) comprising an organic component, where the dispersion degree (the dispersion degree is defined here as a standard deviation relating to a ratio of absorbance of the organic component/absorbance of the rubber component (1) for each 20 samples from the rubber mixture) of the organic component is 0.04 or below and the weight average molecular weight of the rubber component is 300,000 to 2,000,000.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a rubber mixture and a method for producing the same, a molded sheet of the rubber mixture, and a laminated sheet on which these are applied or laminated.
The rubber compound and the like of the present invention can be used in various fields where they have been conventionally used. For example, when the rubber admixture contains a tackifier, it can be suitably used as a pressure-sensitive adhesive composition, and its molded sheet or laminated sheet can be suitably used as a pressure-sensitive adhesive sheet.

[0002]

2. Description of the Related Art Conventionally, rubber blends have been prepared by using a kneader to disperse a compounding agent, a filler and the like in a rubber component as an elastic base polymer. In preparing the rubber mixture, it is preferable to uniformly disperse the compounding agent and the like in the obtained rubber mixture from the viewpoint of various properties of the rubber mixture. Therefore, kneading of a rubber mixture is an important technical point that affects product quality in rubber processing.

[0003] Materials of rubber admixture (rubber component and other components)
An example of an apparatus used for kneading is a batch-type pressure kneader. A schematic diagram of kneading by a batch-type pressure kneader is, for example, as shown in FIG. 1. The rubber admixture material pressed by the pressure lid 1 is kneaded by rotation of the rotor 2. However, in the above-described method using a batch-type pressure kneader, a stagnant portion 3 is formed in the kneader, and a portion where kneading is insufficient occurs, so that the resulting rubber admixture has poor dispersibility as a whole. For example, when the rubber mixture contains a filler as a component other than the rubber component, the filler is present as agglomerated particles in the rubber mixture, and the filler breaks down to a single particle. Often not distributed.

In the above-mentioned method using a batch type pressure kneader, it is conceivable that the kneading time is sufficiently long in order to improve the dispersibility of the rubber admixture. However, in this case, the cutting of the rubber molecules proceeds by the shearing force in the kneading device, and the molecular weight of the rubber component is reduced as compared with before the kneading. On the other hand, as a method of kneading the rubber admixture in a short time, a method of kneading using a Banbury mixer can be considered, but in this method, the load of the shearing force is too large, and the molecular weight of the rubber component rapidly decreases. I will.

In the case where the dispersibility of other components contained in the rubber mixture is poor or the molecular weight of the rubber component is low, various characteristics of various uses using the rubber mixture are considered. Not preferred. For example, in a pressure-sensitive adhesive sheet using a rubber compound obtained by kneading a tackifier and other fillers in a rubber component as a rubber-based pressure-sensitive adhesive, if the dispersibility of the rubber compound is poor, the pressure-sensitive adhesive strength and retention of the pressure-sensitive adhesive are reduced. This results in variations in force and the like. In addition, when the molecular weight of the rubber component decreases, a problem arises in that satisfactory required characteristics cannot be obtained, such as a decrease in the holding power of the pressure-sensitive adhesive.

[0006]

The present invention relates to a rubber mixture obtained by kneading a rubber component (1) and a component (2) other than a rubber component containing an organic component, wherein the dispersibility of the component (2) is It is an object of the present invention to provide a rubber mixture having a good rubber composition and a desired rubber component molecular weight and a method for producing the same, and to provide a molded sheet and a laminated sheet using the rubber mixture.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above problems, and as a result, have found that the above object can be achieved by a rubber compound having the following characteristics, and thereby complete the present invention. Reached.

That is, the present invention relates to a rubber mixture obtained by kneading a rubber component (1) and a component (2) other than a rubber component containing an organic component, wherein the following degree of dispersion of the organic component in the rubber mixture is zero. 0.04 or less and the rubber component has a weight average molecular weight of 300,000 to 2,000,000.

In the present invention, the following degree of dispersion of the organic component dispersed in the rubber mixture is as small as 0.04 or less, and it is recognized that the dispersion of the dispersed organic component is small. The dispersity is preferably 0.04 or less, more preferably 0.03 or less. If the degree of dispersion exceeds 0.04, the dispersibility will be poor, and it will be difficult to obtain satisfactory necessary properties in applications where the rubber admixture is provided. The following degree of dispersion is a value calculated for the organic component contained in the component (2). However, since all the components (2) are kneaded in the same system, the fact that the degree of dispersion is good means that the component (2) It can be presumed that the dispersion is small and the dispersibility is good for all of the cases.

[0010] The degree of dispersion was determined by FT-IR for (20 absorbances of organic component) / 20 samples of the rubber mixture.
The absorbance ratio (a) of (absorbance of the rubber component (1)) and the average value (A) of the absorbance ratio (a) are obtained, and further, the absorbance ratio (a) / average value (A) calculated from these values is obtained. The standard deviation of the value. The measurement of the absorbance of the rubber component (1) and the absorbance of the organic component are values obtained by measuring respective arbitrary characteristic peaks by FT-IR (Fourier transform infrared spectrophotometer).

In the rubber mixture, the rubber component has a weight average molecular weight of 300,000 to 2,000,000, and the rubber molecules of the rubber component (1), which is a material, are hardly cut by kneading. It has the weight average molecular weight of the rubber component required for the blend. The weight average molecular weight of the rubber component is preferably 500,000 to 1.2 million.

In one embodiment of the rubber admixture, the rubber admixture is preferably a pressure-sensitive adhesive composition containing a tackifier as an organic component of the component (2). The degree of dispersion is 0.04 or less. A rubber mixture containing a tackifier is suitable as a pressure-sensitive adhesive composition.

In the rubber mixture, the rubber component (1)
Is preferably natural rubber. Natural rubber is preferable in that a strong adhesive force is obtained, and is particularly useful in the case of an adhesive composition containing a tackifier as an organic component of the component (2).

[0014] The present invention also relates to a process for producing the rubber mixture, wherein the rubber component (1) and the component (2) other than the rubber component containing an organic component are kneaded with a continuous kneader.

Since the continuous kneader continuously supplies the material into the kneader, there is no danger that an insufficient stagnation portion will be generated by kneading, and the component (2) is dispersed without lowering the molecular weight of the rubber component (1). It can be kneaded well.

[0016] The present invention also relates to a molded sheet formed with the rubber mixture. Furthermore, the present invention relates to a method in which the rubber mixture is applied on a base sheet or the formed sheet is laminated.

The rubber mixture of the present invention can be used for various uses as a molded sheet or a laminated sheet. For example, when the rubber mixture is a pressure-sensitive adhesive composition,
It can be used as a pressure-sensitive adhesive sheet or the like.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION As the rubber component (1) as a material in the rubber mixture of the present invention, various rubbers can be used without any particular limitation. For example, in addition to natural rubber,
Synthetic rubbers such as butyl rubber, butadiene rubber, isoprene rubber, and polyisoprene rubber are listed, and these may be used as a blend. Among these rubber components (1), natural rubber is preferred. Natural rubber is
In particular, Mooney viscosity ML _{1 + 4} (100 ° C.) 20-100
Is preferred. When kneading is performed by a continuous kneader, it is preferable to use the rubber component (1) by pulverizing the rubber component (1) into particles having a particle diameter of 20 mm or less in order to improve the feeding accuracy of the rubber component (1).

The component (2) other than the rubber component kneaded with the rubber component (1) contains at least an organic component. The degree of dispersion is determined from the result of measuring the absorbance of the organic component and the absorbance of the rubber component (1) in the rubber mixture.

The organic component includes, for example, a tackifier. The tackifier is for imparting tackiness to the rubber mixture and for facilitating softening by heat, and various resins compatible with the rubber component (1) are used. Various tackifiers such as petroleum resins, phenolic resins, rosin resins, and terpene resins can be used without particular limitation. When a rubber mixture is used as a pressure-sensitive adhesive composition by using a tackifier, the amount of the rubber composition is 20 parts by weight per 100 parts by weight of the rubber component (1).
It is preferably used in an amount of about 200 to 200 parts by weight, more preferably 30 to 150 parts by weight.

Components other than the tackifier used as component (2) include fillers such as calcium carbonate, talc and magnesium oxide, softeners such as polybutene and process oil, antioxidants, plasticizers, crosslinking agents, Various compounding agents such as a coloring agent and an antioxidant are included. The use ratio of these components (2) can be determined appropriately. For example, the amount of the filler used is, per 100 parts by weight of the rubber component (1),
It is about 200 parts by weight or less, preferably 10 to 100 parts by weight. In addition, among these components (2), an organic compound can also be used for measuring the degree of dispersion as the organic component.

The rubber mixture of the present invention is prepared by kneading the rubber component (1) and the component (2) other than the rubber component. As the kneader, those capable of adjusting the degree of dispersion and the weight average molecular weight of the obtained rubber admixture within the above-described predetermined range are used. For example, a continuous kneader such as a planetary continuous kneader or a biaxial continuous kneader is used. It is desirable to knead. In particular, the planetary continuous kneader can pass the material through the nip gap of the plurality of planetary rolls many times at a low shear rate, and can reduce the molecular weight of the rubber component (1) without decreasing the molecular weight of the rubber component (1). ) Can be kneaded with good dispersibility. As a twin-screw continuous kneader, rotor type,
Various types, such as a screw type, a co-rotating type, and a different direction rotating type, are mentioned.

The obtained rubber mixture can be rolled using a calender roll device to form a molded sheet. The calendar roll device is not particularly limited.
Known calender rolls such as a calender roll, a reverse L-three calender roll, a Z-shaped three to four calender roll, and a six calender roll can be used.

Further, a laminated sheet obtained by laminating the molded sheet on a base sheet or applying a rubber mixture can be produced by using a calender roll device. The base sheet is unwound from the raw material, fed out, sent to the nip portion, where it is pressed and laminated with the formed sheet to form a laminated sheet. As the base sheet, known base sheets can be used without limitation, and specifically, papers such as kraft paper, thermoplastic resin films such as PET films, OPP films, polyamide films, polyaramid films, and nonwoven fabrics Etc. are exemplified.

When the rubber mixture is used as a molded sheet, its thickness is about 20 to 3000 μm, and when it is used as an adhesive layer on a laminated sheet, its thickness is about 20 μm.
The thickness is preferably about 500 μm.

[0026]

Next, an embodiment of the present invention will be described in more detail. However, the present invention is not limited only to the following examples.

Example 1 Rubber component (1): Natural rubber SMR was masticated with a mixing roll to obtain a masticated rubber having a Mooney viscosity of ML _{1 + 4} (100 ° C.) 60, and then granulated (6- 10 parts by weight) and component (2): calcium carbonate (average particle size 2.2 μm) 2
0 parts by weight and a material consisting of 100 parts by weight of a petroleum resin (trade name “Quinton S100” manufactured by Nippon Zeon Co., Ltd.) as a tackifier were mixed with a planetary continuous kneader (Entex Co., Ltd.) using a gravimetric feeder. Made, barrel inner diameter 50
mm). The kneader barrel temperature was 110 ° C., the throughput was 30 kg / hour, and the residence time in the apparatus was 5 minutes. The obtained rubber admixture is inverted L4 calender roll (temperature 100
° C), and the rubber mixture is molded into a molded sheet (thickness 25μ).
m) and a substrate sheet (OP having a thickness of 60 μm)
P sheet) at a line speed of 5 m / min to produce a laminated sheet (pressure-sensitive adhesive sheet).

Example 2 In Example 1, a twin-screw continuous kneader (TEM-35, Toshiba Machine Co., Ltd.) was used instead of the planetary continuous kneader.
A rubber mixture was prepared and a laminated sheet was prepared in the same manner as in Example 1 except for using the same.

Comparative Example 1 The same material as in Example 1 was charged into a 5-liter batch type pressure kneader (MS type pressure kneader, manufactured by Moriyama Co., Ltd.) and kneaded for 20 minutes to prepare a rubber admixture. . Thereafter, a laminated sheet was produced in the same manner as in Example 1.

Comparative Example 2 A rubber mixture was prepared in the same manner as in Comparative Example 1, except that the kneading time was changed to 60 minutes. Thereafter, a laminated sheet was produced in the same manner as in Example 1.

The following evaluations were performed on the rubber admixtures and laminated sheets obtained in the examples and comparative examples. Table 1 shows the results.

(Calculation of the degree of dispersion) The rubber mixture was sampled from 20 places in the kneading apparatus, the absorbance was measured by FT-IR (Perkin Elmer Paragon 1000), and the degree of dispersion was calculated according to the definition of the degree of dispersion. Absorbance of the rubber component (1) is carbon in 836cm ^-1 - absorbed carbon double bond, the absorbance of the tackifier is 970 cm ^-1
Was the absorption of the benzene ring. Table 1 shows the average value (A) and the degree of dispersion of the absorbance ratio (a).

(Weight average molecular weight of rubber component) The weight average molecular weight was determined from the molecular weight distribution of the rubber component obtained by GPC measurement. The decrease in molecular weight was based on the weight average molecular weight of the rubber component before kneading.

(Destruction degree of agglomerated particles) For the rubber mixture, the agglomerated particle size of calcium carbonate was measured by observing an X-ray transmission image using an X-ray CT analyzer (manufactured by Nippon Steel Elex Co., Ltd.). did.

(Stability of Laminated Sheet Characteristics) The adhesive strength when used as a pressure-sensitive adhesive sheet was measured by using a 180
° Measured by a peel test. The measurement was performed eight times, and a standard deviation of (measured value) / (average value) was obtained, and this was evaluated as characteristic stability.

[0036]

[Table 1] From the results shown in Table 1, all of the rubber admixtures obtained in Examples have a dispersity of 0.04 or less, have good dispersibility, and have no decrease in molecular weight. It is also recognized that the obtained laminated sheet has stable sheet properties. on the other hand,
In Comparative Example 1, the degree of dispersion exceeded 0.04 and the dispersibility was poor, and the obtained laminated sheet did not have sufficient sheet properties. In Comparative Example 2, the degree of dispersion was 0.04 or less and the dispersibility was good, but the molecular weight was low, and the resulting laminated sheet had problems such as poor sheet properties and low holding power.

[Brief description of the drawings]

FIG. 1 is an example of a conventional batch-type pressure kneader.

[Explanation of symbols]

 1: pressure lid 2: rotor 3: staying part

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 7/00 C08L 7/00 101/00 101/00 // B29K 21:00 B29K 21:00 B29L 7: 00 B29L 7:00 (72) Shuzo Fujiwara 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation (72) Kunihiko Kaita 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Nitto Inside Electric Works Co., Ltd. (72) Inventor Tomoo Yamaguchi 1-2-1, Shimohozumi, Ibaraki-shi, Osaka Nitto Electric Works Co., Ltd. F-term (reference) 4F006 AA12 AB05 AB12 BA13 4F070 AA04 AA05 AC74 AE11 FA03 FB06 4F071 AA10 AA11 AA39 AE22 AH19 BB04 BC01 4F201 AA45 AA45L AB16 AB19 AB28 AD08 AG03 BA01 BA04 BC01 BC03 BC12 BC17 BC37 BD10 BK01 BK18 BK22 BN01 BR02 BR15 BR33 BR37 4J002 AC01W AC03W AC06W AF02X BA01X BB18W CC03X CE0 0X FD34X GT00

Claims (6)

[Claims] In a rubber mixture obtained by kneading a rubber component (1) and a component (2) other than a rubber component containing an organic component, the following degree of dispersion of the organic component in the rubber mixture is 0.04 or less. A rubber mixture wherein the rubber component has a weight average molecular weight of 300,000 to 2,000,000. Dispersion degree: FT-
By IR, (absorbance of organic component) / (rubber component (1))
(A) and the average value (A) of the absorbance ratio (a) and the absorbance ratio (a), and the standard deviation of the absorbance ratio (a) / average value (A) calculated from these values. 2. The rubber admixture is a pressure-sensitive adhesive composition containing a tackifier as an organic component of the component (2), and the degree of dispersion of the tackifier in the rubber admixture is 0.04 or less. The rubber mixture according to claim 1, wherein 3. The rubber mixture according to claim 1, wherein the rubber component (1) is a natural rubber. 4. The rubber mixture according to claim 1, wherein the rubber component (1) and the component (2) other than the rubber component containing an organic component are kneaded by a continuous kneader. Manufacturing method. 5. A molded sheet on which the rubber mixture according to claim 1, 2 or 3 is molded. 6. A laminated sheet wherein the rubber mixture according to any one of claims 1 to 3 is applied on a base sheet, or the molded sheet according to claim 4 is laminated.