JPS62233515A - Rubber roll - Google Patents

Abstract

PURPOSE:To increase the hardness of a roll and to reduce the impact noise of printing by forming a rubber cylinder composed of a rubber composition containing a reinforced rubber composition mixed with a thermoplastic polymer integrally over a metallic core. CONSTITUTION:A rubber cylinder to be formed integrally over a metallic or resin core is composed of a reinforced rubber composition composed of natural rubber or polyisoprene rubber and vulcanizable rubber mixed with short fibers of thermoplastic polymer. Short micro fibers of nylon 6, polyurethane, etc. are suitable as said short fibers of thermoplastic polymer and burried in a vulcanizable rubber in the form of short fibers with molecules being arranged in the axial direction of fibers. The thermoplastic short fibers are mixed by 2-30wt% for 100wt% of the entire rubber component of rubber composition.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rubber roll, and particularly to a rubber roll suitable for use in office equipment such as printers, typewriters, copying machines, and word processors.

[Prior Art] Rolls used in office equipment such as printers, typewriters, copying machines, and word processors, such as platen rolls and paper feed rolls, generally have a rubber cylindrical body integrally formed with a metal core. It is said that the configuration is as follows.

These rolls are required to have high hardness (for example, JIS hardness of 90° or more).

Conventionally, the materials for the rubber cylindrical bodies of these rolls were:
A rubber composition in which 50 parts by weight or more of carbon black or an inorganic filler such as silica or magnesium carbonate is blended with styrene-butadiene copolymer rubber, chloroprene rubber, or urethane rubber to impart desired high hardness, specifically A high styrene-butadiene copolymer rubber having a styrene content of 30% by weight or more and 50 parts by weight or more of carbon black is used, or a methacrylic rubber as disclosed in Japanese Patent Publication No. 59-25884 is used. Improvements have been made, such as using materials with reactive reinforcing fillers such as zinc.

[Problems to be solved by the invention] However, in recent years, with the advancement of office e-automation, many types of office equipment have been introduced into offices, such as word processors, typewriters,
Noise generated from printers and the like is becoming a new problem. In other words, the printing mechanisms of these devices, as typified by wire tod printers, are often configured to print by hitting a platen roll with type through paper. This impact generates considerable noise.

In addition, especially for such printing rolls, in order for the printing performance to be at a satisfactory level, the roll hardness must be 90' or higher in JIS hardness, and the surface accuracy and dimensional accuracy of the roll must be sufficiently guaranteed. However, in this regard, conventional rolls do not provide sufficiently satisfactory performance.

[Means for Solving the Problems] In view of the above-mentioned circumstances, the present invention has been made to reduce the noise of platen rolls, etc., and to provide a roll with excellent printing performance and processing properties. , on a metal core or resin core, ■ one type selected from the group consisting of natural comb, polyisoprene rubber, styrene-butadiene copolymer rubber, polychloroprene rubber, ethylene-propylene copolymer rubber, and polybutadiene rubber. or two or more types; ■ A reinforced rubber in which short fibers of a thermoplastic polymer having (C-NH)- groups in the molecule are grafted to a vulcanizable rubber via an initial condensate of a phenol formaldehyde resin. A rubber roll, characterized in that a rubber cylindrical body made of a rubber composition containing a composition is integrally formed.
The main points are as follows.

As a result of extensive research in order to obtain roll hardness that provides sufficient printing performance and to reduce the impact noise during printing, the inventors first discovered the following about the mechanism of noise generation when the roll hits. I gained this knowledge.

In other words, the roll impact sound generation mechanism is such that the impact of the impact from a printing mechanism such as a wire tod is transmitted to a core made of metal or the like via the rubber cylindrical body of the roll, which further vibrates the entire device to generate noise. This is the result. Therefore, in order to reduce noise, it is sufficient to reduce the vibration transmission rate of the rubber material of the rubber cylindrical body of the roll.

Generally, the vibration transmissibility T is expressed as the viscous resistance C for an object of mass M.
' acts on the static spring constant, and is expressed by the following equation (I) in a one-degree-of-freedom mass vibration system model.

Equation (I) for this vibration transmissibility T is as follows for high-speed impact such as in a printer, so (K' + CW) /K', that is, the ratio of the dynamic spring constant to the static spring constant. , the vibration transmission rate T can be reduced by reducing the so-called dynamic magnification.

Therefore, in order to obtain a roll with less impact noise, it is sufficient to use a rubber composition with a small dynamic magnification as the material for the rubber cylinder.On the other hand, conventional methods have been used to obtain high hardness in the rubber material of the roll. Rubber compositions containing a large amount of fillers or using reactive reinforcing fillers have a high dynamic ratio.
In addition, conventionally used styrene with high styrene content
Butadiene copolymer rubber and the like also increase the dynamic ratio of the resulting rubber composition, and are not preferred in terms of noise generation.

Based on these findings, the present inventors conducted further studies to obtain a rubber composition with high hardness and excellent printing performance without increasing the dynamic magnification. As a result, the present inventors formulated a rubber composition with short Ti & fibers of a specific thermoplastic polymer. The present invention was completed based on the discovery that a high hardness 12 degree rubber composition can be obtained without increasing dynamic magnification by reinforcing the rubber.

The rubber roll of the present invention has a rubber cylindrical body made of a rubber composition with a small dynamic magnification and high hardness, which is blended with short fibers of thermoplastic polymer, and is integrally formed on a core body, so that the impact noise is reduced. A rubber roll with low vibration transmission rate, low noise, and excellent printing performance.

The present invention will be explained in detail below.

In the present invention, a normal core made of metal or resin is used as the core forming the roll drive shaft.

In the present invention, the rubber cylindrical body integrally formed with such a core body is made of natural rubber, polyisoprene rubber, styrene-butadiene copolymer rubber, polychloroprene rubber, ethylene-propylene copolymer rubber, polybutane An initial condensation product of one or more selected from the group consisting of phenol-formaldehyde-based resin and short fibers of a thermoplastic polymer having 100 NH- groups in the molecule in vulcanizable rubber and one or more selected from the group consisting of a reinforced rubber composition grafted through the rubber composition.

In the present invention, natural rubber is particularly preferred as the rubber in the rubber composition constituting the rubber cylinder. Also, ■
As the reinforced rubber composition, for example, one manufactured as follows is suitable.

That is, vulcanizable rubber, short fibers of thermoplastic polymer having a molecular weight of less than 200,000 and having 100 NH groups in the polymer molecule, and the total amount of these rubber and thermoplastic polymer is 10
An initial condensate of phenol formaldehyde resin in an amount of 0.2 to 5 parts by weight per 0 parts by weight and a compound that can generate formaldehyde when heated are kneaded at a temperature above the melting point of the thermoplastic polymer and below 270 ° C. , to obtain a kneaded product.

The obtained mixed material has a ratio of rubber and thermoplastic polymer in the kneaded material of 1 to 100 parts by weight of thermoplastic polymer per 100 parts by weight of rubber.
If the amount is 100 parts by weight, add as is; if the ratio of rubber and thermoplastic polymer in the kneaded material exceeds 100 parts by weight of thermoplastic polymer per 100 parts by weight of rubber, add additional vulcanizable rubber to 100 parts by weight of the entire rubber. Thermoplasticity 1 part by weight
The mixture is added to the kneaded product in an amount of 100 parts by weight, and further kneaded using a thermoplastic polymer melting point tool at a temperature of 270° C. or lower to obtain a reinforced rubber composition.

Structure of such a reinforced rubber composition: # Among the components, as the vulcanizable rubber, all rubbers that give a rubber elastic body by vulcanization can be used, such as natural rubber, Cis-1,4-polybutadiene, polyisoprene, polychloroprene, styrene-butadiene copolymer rubber, inprene-ifthylene copolymer comb, ethylene-propylene-nonconjugated diene ternary copolymer rubber, or two or more of these Mixtures may be mentioned.

Among these rubbers, natural rubber, which does not gel in the molding process described below, is most preferred.

In addition, for short fibers of thermoplastic polymer, molecular weight 2
less than 0,000, melting point is 190-235°C, preferably 19
Nylon such as nylon 6, nylon 610, nylon 12, nylon 611, nylon 612, polyurea or polyurethane such as polyhebutamethylene urea, polyundecamethylene urea, etc., particularly preferably 200 to 220 °C. 100NH- in polymer molecules such as
Examples include fine staple fibers of thermoplastic polymers having groups. Among these, nylon is particularly preferred, and its fibers have an average diameter of 0.05 to 0.87 pm, a circular cross section, and a shortest fiber length of Ig, m or more. These fibers are preferably embedded in the vulcanizable rubber in the form of fine short fibers with molecules arranged in the fiber axis direction.

The initial condensate of the phenol formaldehyde resin is a resol type alkylphenol formaldehyde resin represented by the following general formula, for example, a resol type obtained by reacting an alkyl phenol such as cresol with formaldehyde or acetaldehyde in the presence of an alkali catalyst. Examples include initial condensates and modified products thereof. In this case, the resol type alkylphenol formaldehyde resin having two or more methylol groups in the molecule is particularly suitable.

Furthermore, as a phenol formaldehyde resin, for example, phenols such as phenol and bisphenols and formaldehyde (paraformaldehyde may also be used) using an acid such as sulfuric acid, hydrochloric acid, phosphoric acid, or oxalic acid as a catalyst.
Novolak-type phenol formaldehyde resins such as soluble and fusible resins obtained by condensation reaction with and modified products thereof can be mentioned. In this case, suitable novolak-type phenol-formaldehyde-based resins include, for example, novolak-type phenol-formaldehyde initial condensate, novolak-type lactam-bisphenol F-formaldehyde initial condensate, novolak-type styrenated phenol-phenol-formaldehyde initial condensate, etc. .

In the present invention, the reinforced rubber composition is made of fine short fibers of a thermoplastic polymer having 100 NH- groups in the polymer molecule for 100 parts of the above-mentioned vulcanizable rubber.
It is preferred that 100 parts by weight - 1 part by weight, preferably 1 to 70 parts by weight, particularly preferably 30 to 70 parts by weight, are embedded.

In addition, the reinforcing rubber composition is made of thermoplastic polymer through the initial condensation product of phenol formaldehyde resin at the interface of the fine short fibers of thermoplastic polymer embedded in the vulcanizable rubber. The grafting ratio, expressed as the percentage by weight of the vulcanizable rubber (vulcanizable rubber/fine short fibers of thermoplastic polymer) grafted onto the vulcanizable rubber, is 3 to 25% by weight, in particular 5 to 20% by weight. Therefore, it is preferable that the thermoplastic polymer forming the fiber and the vulcanizable rubber are graft-bonded via an initial condensate of phenol formaldehyde resin.

In order to produce the rubber roll of the present invention, suitable amounts of the rubber (1) and the reinforced rubber composition (2) described above are blended and kneaded to obtain a rubber composition, and this is applied to the surface of the metal core or resin core. Vulcanize and mold into the desired shape.

In this case, the blending ratio of the rubber (2) and the reinforced rubber composition (2) is such that the proportion of short fibers of the thermoplastic polymer is 2 parts by weight based on 100 parts by weight of the total rubber components of the rubber composition obtained.
It is preferable to adjust the amount to 30 parts by weight, particularly 5 to 15 parts by weight.

In addition, in the present invention, in the rubber composition consisting of the rubber (1) and the reinforced rubber composition (2), carbon black, an inorganic filler, a process oil, a vulcanizing agent, a vulcanization accelerator, Compounding agents such as anti-aging agents may also be added. In addition, when blending carbon black and inorganic fillers,
The blending amount thereof is preferably 20 parts by weight or more per 100 parts by weight of the rubber composition.

[Examples] The present invention will be described in more detail with reference to Examples and Comparative Examples below, but the present invention is not limited to the following Examples unless it exceeds the gist thereof.

The reinforced rubber compositions used in the examples were manufactured according to the following manufacturing examples.

Production Example A 00C Banbury mixer (manufactured by Kobe Steel) set at 150°C and 1100 rpm had a Mooney viscosity of 2 at 100°C.
1400 g of natural rubber of No. 5 and N-(3-methacryloyloxy-2-hydroxypropyl)-N-phenyl-p
- 14 g of phenylene diamine (trade name: Nicklac G-1, manufactured by Ohmukai Shinko Chemical Industry ■) was added, and after mastication for 1 minute, 6-nylon (trade name: 1030B, manufactured by Ube Industries, Ltd., melting point 221 'C1) was added. 700 g of molecular weight 30,000) was added and kneaded for 7 minutes. During this time, the temperature inside the mixer rose to 232°C, and the 6-nylon melted.

Next, 30 g of novolak-type phenol formaldehyde initial condensate (trade name: 550PL, manufactured by Showa Kasei ■) was added and kneaded for 7 minutes, and then 3 g of hexamethylenetetramine was added and kneaded for 2.5 minutes (during which time (The temperature of the mixer was 230°C) A graft reaction was carried out to obtain a reinforced rubber composition.

Examples 1 and 2, Comparative Examples 1 and 2 A rubber cylindrical body made of a rubber composition having the composition shown in Table 1 was integrally formed on a metal core (proper vulcanization at 155° C1).
We manufactured platen rolls for printers and measured and evaluated their characteristics. The results are shown in Table 1.

Note that *1 to 3 in Table 1 indicate the following.

*lSBR: Japan Synthetic Rubber 5BR1502 bound styrene 23.5% by weight *2H3R: High styrene resin H3R manufactured by Nippon Synthetic Rubber Co., Ltd.
OO61 *3FRR: Composition ratio (weight) of the reinforced rubber composition obtained in Production Example 1: Nylon: Natural rubber = 50: 100 In addition, the hardness is JIS hardness, and the static elastic modulus Es is 5%
Static elastic modulus during stretching. The dynamic elastic modulus E', loss coefficient tan δ, and dynamic magnification E'/Es were measured using a viscoelastic spectrometer (manufactured by Makimoto Seisakusho ■) at 25°C and a vibration frequency of 1.
Measured at 0.00Hz and dynamic strain of 0.3%.

The noise level (octave band level dBA) is expressed using the results of Comparative Example 1 as a control.

Note that the noise levels in Comparative Example 1 were O and A.

= 61.8 dBA, 2-4 KHz = 60.8 dBA. Printability was evaluated by actually using each platen roll.

From Table 1, it is clear that the rubber composition according to the present invention has high hardness and good printability, has a small dynamic magnification, and has a significantly reduced noise level.

Table 1 [Effects of the Invention] As detailed above, the rubber roll of the present invention has, on the core,
A rubber cylindrical body made of a rubber composition containing a reinforced rubber composition blended with short fibers of a specific thermoplastic polymer is integrally formed, and the rubber composition according to the present invention has extremely high hardness. Furthermore, since the dynamic magnification is small, a rubber roll with excellent printing performance and low impact noise caused by printing can be provided.

Therefore, according to the present invention, noise caused by various office equipment can be prevented, and a good working environment in the office can be maintained.

The rubber roll of the present invention is extremely effective for platen rolls of typewriters, printers, word processors, etc., but is also extremely effective for paper feed rolls of various office equipment such as copying machines and facsimile machines. suitable.

Claims (2)

[Claims] (1) On the metal core or resin core, [1] Natural rubber, polyisoprene rubber, styrene-butadiene copolymer rubber, polychloroprene rubber, ethylene-
One or more selected from the group consisting of propylene copolymer rubber and polybutadiene rubber, and [2] Vulcanizable rubber, a thermoplastic polymer having a ▲ mathematical formula, chemical formula, table, etc. in the molecule. A rubber roll integrally formed with a rubber cylindrical body made of a reinforced rubber composition to which short fibers of are grafted via an initial condensation product of a phenol formaldehyde resin, and a rubber composition containing. (2) Claim 1, characterized in that the proportion of short fibers of the thermoplastic polymer in the rubber composition forming the rubber cylinder is 2 to 30 parts by weight based on 100 parts by weight of the total rubber components. Rubber rolls as described in section.