JP2021133484A - Workpiece-holding sheet - Google Patents

Abstract

To provide a workpiece-holding sheet particularly suitable for holding a workpiece needing the simultaneous polishing of a plain face and outer peripheral side face, and having no remanence of an adhesive component on the workpiece at the time of polishing completion.SOLUTION: This invention relates to a non-foamed urethane resin layer 11 to which a workpiece 1 adheres, and a workpiece-holding sheet 7 bonded to a face opposite to the holding face of the above resin layer 11. The non-foamed urethane resin layer 11 is configured by bond of a dangling chain comprising a diol compound and/or polyol compound to a mesh-like cross-link structure in which an isocyanate group-terminal prepolymer is cross-linked by three or more functional polyol compounds and three-functional isocyanurate compounds.SELECTED DRAWING: Figure 2

Description

The present invention relates to a work holding sheet, and more specifically, has a non-foamed urethane resin layer having a holding surface in close contact with the work, and a foamed resin layer bonded to a surface side opposite to the holding surface of the non-foamed urethane resin layer. Regarding the work holding sheet.

Conventionally, in a device for grinding and polishing a plate-shaped work surface such as a semiconductor substrate, glass, metal, resin, or ceramics, processing is performed while the work is held on a holding surface plate. For example, it is held by using an adhesive tape or a fixing material containing paraffin as a main component (Patent Documents 1 and 2), or by using a resin work holding sheet (Patent Documents 3 and 4). ..
On the other hand, metal or resin housings are used to form mobile terminals such as mobile phones and smartphones, and curved surfaces are formed on the outer periphery of the housing for the purpose of design differentiation. Is being formed.
When manufacturing such a housing, a curved shape is formed on the outer periphery of the material by cutting or die molding, but it is necessary to polish the cutting marks and burrs formed on the entire surface of the work after that.
At that time, an elastic polishing pad is pressed against the housing held by the holding surface plate, and the polishing pad is polished while being deformed according to the shape of the housing so that the side surface and the curved portion are polished. It has become.

Japanese Patent No. 3163614 Japanese Unexamined Patent Publication No. 2007-326208 Japanese Unexamined Patent Publication No. 2005-224888 Japanese Patent No. 4569273

When polishing a work that needs to be polished at the same time on the flat surface and the outer peripheral side surface like the housing of the portable terminal described above, the following performance is required as the work holding sheet for holding the work on the holding surface plate. NS.
First, a holding force is required to hold the work so that it does not separate from the work holding sheet during polishing. Especially in the case of a work that needs to polish the flat surface and the outer peripheral side surface at the same time, unlike the flat surface polishing of a semiconductor substrate or a glass substrate, the stress from the polishing pad also acts on the side surface of the work, so that the stress in the horizontal direction is applied to the side surface of the work. Must be held so that the work does not come off even if it acts.
Secondly, when the work is separated from the holding surface plate at the end of polishing, the adhesive component of the work holding sheet does not remain on the work, and the work holding sheet is required to have removability so that the work holding sheet can be used repeatedly. If the adhesive component remains on the work, cleaning work of the work is required, and the adhesive component is transferred from the work holding sheet to the work, so that the work holding sheet cannot be used repeatedly.
When the work is held by using an adhesive tape or paraffin as in Patent Documents 1 and 2, a step of cleaning the adhesive component adhering to the work is required after polishing is completed, and the acrylic pressure-sensitive adhesive of Patent Document 3 Even in the work holding sheet using the above, the adhesive component may remain on the work, and a cleaning step is required.
On the other hand, the work holding sheet used in Patent Document 4 has a non-foaming resin layer and does not leave adhesive components, but is used for precision surface polishing of semiconductor substrates and the like, so that it is horizontal to the work. In some cases, it could not be retained when stress was applied.
In view of such a problem, the present invention is particularly suitable for holding a work having a plate thickness, and provides a work holding sheet in which no adhesive component remains on the work at the end of polishing.

That is, the work holding sheet according to the invention of claim 1 has a non-foamed urethane resin layer having a holding surface in close contact with the work and a foamed resin layer bonded to a surface side opposite to the holding surface of the non-foamed urethane resin layer. In the work holding sheet with
The non-foamed urethane resin layer has a network crosslinked structure in which the isocyanate group-terminated prepolymer is crosslinked with a trifunctional or higher functional polyol compound and a trifunctional isocyanurate compound, and a dungling chain composed of a diol compound and / or a polyol compound is formed. It is characterized by being combined.

According to the invention of claim 1, the form in which the cohesive force is enhanced while having a certain degree of softness by containing a trifunctional or higher functional polyol as the polyol compound constituting the urethane resin composition of the non-foaming urethane resin layer. It is possible to exert adhesive strength and removability.
In addition, diol compounds and / or polyol compounds form dungling chains, resulting in high surface tackiness and tear resistant properties.
From the above, even if stress in the horizontal direction acts on the work thickness portion, it can be retained, and when the work is detached, there is no residual adhesive component and it can be reused. It has become.

Schematic cross-sectional view when the work is held and polished by the work holding sheet according to this embodiment. Schematic cross-sectional view of the work holding sheet according to this embodiment Conceptual diagram of urethane resin composition constituting the non-foaming urethane resin layer The figure explaining the action by the urethane resin composition The figure explaining the action by the urethane resin composition

Hereinafter, the present invention will be described with respect to the illustrated embodiment. FIG. 1 shows a polishing device 2 for polishing the work 1, and the polishing device 2 is provided above the holding surface plate 3 for holding the work 1 and below. It is provided with a polishing surface plate 5 for holding the polishing pad 4, and a slurry supply means (not shown) for supplying a slurry (polishing liquid) between the work 1 and the polishing pad 4.
The work 1 of this embodiment is a metal or resin housing used for mobile phones, smartphones, etc., and the work 1 has a thickness of, for example, 3.0 to 30.0 mm, and has a thickness of 3.0 to 30.0 mm on the outer periphery thereof. Is formed with a curved portion 1a having a radius of 1.5 to 15.0 mm.
The work 1 is formed by a method such as cutting or mold forming, and the polishing apparatus 2 of the present embodiment smoothly polishes the work 1 while removing cutting marks during cutting and burrs during molding. In particular, not only the surface of the work 1 (lower surface in the drawing) but also the side surface and the curved portion 1a are polished at the same time.

The holding surface plate 3 and the polishing surface plate 5 each have a substantially disk shape, and each of them rotates with each other by a driving means (not shown), and the polishing surface plate 5 is provided so as to be able to move up and down.
In the polishing apparatus 2 of this embodiment, a plurality of works 1 can be polished at the same time, and the holding surface plate 3 has a plate-shaped carrier 6 for holding the plurality of works 1 in a predetermined arrangement. Is provided, and the work 1 is arranged inside a plurality of holding holes 6a formed in the carrier 6.
Each work 1 is held on the surface of the work holding sheet 7 mounted on the surface of the holding surface plate 3, and when the work 1 is mounted on the holding surface plate 3, the work 1 is mounted on the work. It is designed to be pressed against the holding surface of the holding sheet 7.
The work 1 is adsorbed and held on the work holding sheet 7 by interaction, but at this time, it is not necessary to interpose a liquid such as water between the work 1 and the work holding sheet 7.
Then, the work 1 held by the work holding sheet 7 is held in a state of protruding downward from the holding hole 6a of the carrier 6, and the surface, side surface, and curved portion 1a of the protruding work 1 are supported by the polishing pad 4. It is possible to polish.

A polishing pad 4 having a substantially disk shape is fixed to the upper surface of the polishing surface plate 5 with double-sided tape or the like. In this embodiment, since it is particularly necessary to polish the curved portion 1a of the work 1, the polishing pad 4 has a required thickness and a required compressive elasticity.
When polishing the work 1 using the polishing device 2, the polishing pad 4 is rotated and pressed against the work 1, whereby the polishing pad 4 is deformed according to the shape of the work 1 and the surface, side surface, and curvature of the work 1 are curved. The part 1a is polished.
Further, when the work 1 is polished, the slurry supply means supplies the slurry between the work 1 and the polishing pad 4.

As shown in FIG. 1, when the work 1 having a thickness is polished by the polishing device 2 of the present embodiment, the stress F2 acting on the flat surface of the work 1 is applied because the polishing pad 4 is deformed and brought into contact with the work 1. In addition, the stress F1 from the horizontal direction acting on the side surface of the work acts.
Therefore, the work holding sheet 7 of this embodiment needs a holding force that holds the work 1 so that it does not fall off even if a stress F1 in the horizontal direction acts on the work 1.
If the holding force of the work 1 is insufficient, the work 1 may fall off from the work holding sheet 7 during the polishing work, or the outer peripheral edge of the work 1 may be peeled off from the work holding sheet 7, and polishing debris may be generated between them. There is a risk of getting in and damaging the work 1.
On the other hand, it is necessary to remove the work 1 from the holding surface plate 3 after the polishing is completed. At this time, if the adhesive component of the work holding sheet 7 remains on the work 1, the work 1 must be washed, and the work 1 must be washed. Since the adhesive component of the holding sheet 7 itself is also transferred to the work, the work holding sheet 7 cannot be reused.
Therefore, the work holding sheet 7 needs to have removability so that when the work 1 is separated from the work holding sheet 7, the adhesive component does not remain on the work 1 and the work holding sheet 7 after use can be reused. It becomes.
The work holding sheet 7 according to the present invention can hold the work 1 which needs to be polished on the flat surface and the outer peripheral side surface at the same time even if a stress in the horizontal direction acts on the work 1, and when the work 1 is separated. Has no residual adhesive component and can be reused.

Hereinafter, the work holding sheet 7 in this embodiment will be described in detail. FIG. 2 shows a schematic cross-sectional view of the work holding sheet 7, and the upper surface of the drawing is a holding surface for holding the work 1.
The work holding sheet 7 of this embodiment is joined to the non-foaming urethane resin layer 11 made of the urethane resin composition on which the holding surface is formed and the surface side opposite to the holding surface of the non-foaming urethane resin layer 11. It is composed of a foamed resin layer 12. Further, as will be described later, the non-foaming urethane resin layer 11 and the foamed resin layer 12 are chemically bonded, and an adhesive layer is not required between them.
In this embodiment, the thickness of the non-foamed urethane resin layer 11 is preferably 20 to 50 μm, and more preferably 25 to 45 μm. The thickness of the foamed resin layer 12 is preferably 150 to 1400 μm, and more preferably 200 to 1000 μm. As a result, it is possible to achieve both the retention property and the re-peelability of the thick work 1 as described above.
The work holding sheet 7 of this embodiment holds the work 1 by the interaction between the holding surface and the surface of the work 1 by pressing the work 1 against the holding surface of the non-foamed urethane resin layer 11. Therefore, it is preferable that the work holding sheet 7 of this embodiment does not form through holes or grooves on the holding surface of the non-foamed urethane resin layer 11.

First, the non-foaming urethane resin layer 11 may have bubbles that do not substantially have foaming and may have bubbles that can be mixed in the actual manufacturing process, but the number of bubbles is smaller. Is preferable.
Specifically, the perforation area ratio may be 3% or less, preferably 2% or less, and more preferably 1% or less. For the opening area ratio, for example, the holding surface is magnified 175 times and observed, and the obtained image is binarized by image processing software (Image Analyzer V20LAB Ver. 1.3, manufactured by Nikon) to obtain the number of bubbles. And the area of each bubble (opening diameter) can be measured to calculate the open hole area ratio per unit area.

Next, the urethane resin composition constituting the non-foamed urethane resin layer 11 forms a network-like crosslinked structure crosslinked by the isocyanate group-terminated prepolymer, the trifunctional or higher functional polyol compound, and the trifunctional isocyanurate compound. It is composed of a network structure in which a dungling chain composed of a diol compound and / or a polyol compound is bonded.
Examples of the urethane resin composition include polyester-based polyurethane resin, polyether-based polyurethane resin, and polycarbonate-based polyurethane resin, and one of these can be used alone or in combination of two or more.
Among these, a polyether polyurethane resin is preferable from the viewpoint of more effectively and surely fulfilling the object of the present invention.

The NCO equivalent of the urethane resin composition constituting the non-foamed urethane resin layer is preferably 300 to 600, more preferably 350 to 550. When the NCO equivalent of the urethane prepolymer is within the above range, the holding power and cushioning property of the work 1 tend to be further improved.
Further, in this example, an equivalent ratio (NCO / OH) of the number of isocyanate groups (NCO) contained in the urethane resin composition constituting the non-foamed urethane resin layer and the number of hydroxyl groups (OH) contained in the above-mentioned polyol compound. ) Is preferably in the range of 0.7 to 1.3.
When the equivalent ratio (NCO / OH) is 0.7 or more, appropriate flexibility can be obtained without the crosslink density becoming too high, and when it is 1.3 or less, it is bonded to the foamed resin layer. Since it is possible to secure a large number of dungling chains, which will be described later, in which one end is a free end while maintaining the cohesive force, it is possible to secure the wettability of the dungling chains.
In the present specification, the "NCO equivalent" means the average NCO equivalent in the urethane resin composition constituting the non-foamed urethane resin layer. Further, the NCO equivalent can be measured by a well-known method, and can be measured according to, for example, JISK7301 (1995).

Further, by adding a trifunctional isocyanurate compound together with the above-mentioned isocyanate group-terminated prepolymer, it is possible to contribute to the formation of a network-like polyurethane crosslinked structure described later.
Examples of the trifunctional isocyanurate compound include an isocyanurate form of a hexamethylene diisocyanate compound, an isocyanurate form of an isophorone diisocyanate compound, an isocyanurate form of a tolylene diisocyanate compound, an isocyanurate form of a xylylene diisocyanate compound, and a hydrogenated xylylene diisocyanate compound. It is preferable that at least one selected from the group of compounds consisting of isocyanurates.
The trifunctional isocyanurate compound is preferably contained in the range of 2 to 20% by mass and 4 to 15% by mass with respect to the entire polyurethane resin composition constituting the non-foaming urethane resin layer. More desirable.
When the amount is more than 2% by mass, the network polyurethane crosslinked structure can be developed and the dungling chain can be efficiently introduced into the network structure. When the amount is 20% by mass or less, the crosslink density becomes dense. The flexibility of the non-foamed urethane resin layer 11 can be maintained without becoming too brittle.

Next, as the chain extender, a trifunctional or higher functional polyol is used in this example to form a part of the network-like polyurethane crosslinked structure.
As the trifunctional or higher functional polyol, trimethylolpropane, pentaerythritol, or polypropylene glycol having a molecular weight of 3000 to 6000 can be used.
By using a trifunctional or higher functional polyol, the cohesive force can be enhanced while having a certain degree of softness, and the adhesive force and removability as the work holding sheet 7 can be exhibited.

Next, the polyol compound that is urethane-bonded to the network-like crosslinked structure and functions as a dungling chain is not particularly limited as long as it is a polyol having a saturated or unsaturated aliphatic group dungling chain having 10 to 30 carbon atoms. ..
For example, it may contain a diol compound having a dungling chain of a saturated or unsaturated aliphatic group having 10 to 30 carbon atoms and / or a polyol compound having two or more hydroxyl groups, and has an activity of reacting with other isocyanate groups. An active hydrogen compound having two or more hydrogen groups can also be used in combination.
Active hydrogen groups such as hydroxyl groups of polyol compounds react with isocyanate groups of urethane prepolymers to form urethane bonds. At this time, the saturated or unsaturated aliphatic group having 10 to 30 carbon atoms of the diol compound becomes a dungling chain having 10 to 30 carbon atoms.
By using the diol compound and / or the polyol compound, a dungling chain having a length proportional to the molecular weight of the diol compound and / or the polyol compound can be introduced.
Examples of the diol compound include a compound represented by the following formula (1).
HO- (R (R "))-OH (1)
Specific examples of the diol compound are not particularly limited, but for example, glyceryl caprate, glyceryl laurate, glyceryl myristate, glyceryl pentadecylate, glyceryl palmitate, glyceryl margarate, glyceryl stearate, glyceryl arachidate, glyceryl henicosylate. Glycerin saturated fatty acid esters such as glyceryl behenate, glyceryl lignocerate, glyceryl serotate, glyceryl montanate, glyceryl melisinate; Examples thereof include glycerin unsaturated fatty acid esters such as glyceryl, glyceryl eleostearate, glyceryl arachidate, glyceryl arachidate and glyceryl nervone.
Examples of the polyol compound include polyol compounds having R "in the above formula (1), and more specifically, without particular limitation, polyglycerin such as diglyceryl monooleate and decaglyceryl trioleate. Examples include fatty acid esters.
The carbon number of the aliphatic group (for example, R ") in the diol compound and / or the polyol compound is preferably 10 to 30, more preferably 15 to 25, and further preferably 16 to 24. When the carbon number of the aliphatic group of the above is within the above range, the holding power to the object to be polished tends to be further improved.
The content of the diol compound and / or the polyol compound is preferably 20 to 45% by mass, more preferably 25 to 40% by mass, based on the total amount of the urethane resin composition constituting the non-foaming urethane resin layer. ..
By adjusting the content of the diol compound and / or the polyol compound, the number of dungling chains to be introduced can be controlled, and the adsorption force can be adjusted by controlling the number of chains.
The diol compound and / or the polyol compound constitutes a dungling chain having a free end in which one end is bonded to the network-like polyurethane crosslinked structure and the other end is not connected to the crosslinked structure.
In this embodiment, each dungling chain having a molecular weight of about 200 to 400 is used, whereby the non-foamed urethane resin layer 11 exhibits adhesiveness to the work 1.
When the molecular weight of the dangling chain is within the above range, it is expected that the initial tackiness to the work is excellent and the adsorption force is improved against the stress in the horizontal direction.

The shore A hardness of the work holding sheet 7 is preferably 5 to 70 °, more preferably 8 to 60 °, still more preferably 20 to 55 °, and particularly preferably 10 to 40 °.
When the shore A hardness of the work holding sheet 7 is 5 ° or more, the durability tends to be further improved. Further, when the shore A hardness is 70 ° or less, the cushioning property is further improved, and when the work 1 and the holding surface are in close contact with each other, the holding force is further improved.
The shore A hardness of the work holding sheet 7 can be controlled by the density of the foamed resin layer 12, the resin modulus, or the like.

The compressibility of the work holding sheet 7 is 1 to 60%, preferably 2 to 55%, and more preferably 3 to 50%. When the compression rate is 1% or more, the impact during polishing can be absorbed and the work can be suppressed from falling off.
Further, when the compressibility is 60% or less, the followability to the work is improved and the surface roughness of the work is reduced. The compressibility can be adjusted by adjusting the density and hardness of the foamed resin layer.
Further, the compressibility of the work holding sheet 7 can be measured by using a shopper type thickness measuring device (pressurized surface: circular with a diameter of 1 cm) in accordance with Japanese Industrial Standards (JIS L 1021).
Specifically, the thickness t0 after being pressurized with the initial load for 30 seconds is measured, then the thickness t1 after being left for 1 minute under the final pressure is measured, and the compressibility is calculated by the following formula (2). Can be calculated. At this time, the initial load is 300 g / cm ² and the final pressure is 1800 g / cm ² .
Formula (2): Compressibility (%) = (t0-t1) / t0 × 100

（式中、Ｒ及びＲ’は、ポリウレタンの主鎖を構成する有機基を示し、Ｒ”は、Ｒに結合したダングリング鎖を示す。） FIG. 3 schematically shows a urethane resin composition forming the non-foaming urethane resin layer 11, and is a dangle ring having a free end at one end with respect to a network-like crosslinked structure 13 made of polyurethane. It has a structure in which chains 14 are bonded.
Expressing this with a chemical formula, the crosslinked structure of polyurethane has a repeating unit represented by the following chemical formula (1). In the chemical formula (1), the dungling chain 14 is a portion represented by R ”.

(In the formula, R and R'indicate the organic groups constituting the main chain of polyurethane, and R'indicates the dungling chain bonded to R.)

By introducing the dungling chain 14 into the network-like crosslinked structure 13 in this way, the non-foamed urethane resin layer can be kept soft to some extent.
Since one end of the dangling chain 14 is not connected to the crosslinked structure, it exhibits high surface adhesiveness, and the partial chains having one end free penetrate each other within the molecule to exhibit cohesive force due to entanglement. , Removability is exhibited.
Then, the dungling chain 14 has high flexibility and can be brought into close contact with each other so as to follow the fine irregularities on the surface of the work 1, and the intermolecular force acting between the surface of the work 1 and the non-foamed urethane resin layer is increased. , Contributes to the holding power of the work 1.
Since the intermolecular force with the work 1 is weaker than the force with which the dungling chain 14 binds to the network crosslinked structure 13, the dungling chain 14 is less likely to be broken when the work 1 is separated from the non-foamed urethane resin layer 11. Since peeling occurs between the work 1 and the work holding sheet 7, the re-peeling property is excellent.

FIG. 4 schematically shows the action when the work 1 is brought into close contact with the non-foamed urethane resin layer 11, and the lower line in the drawing shows a part of the mesh-like crosslinked structure 13, and the mesh-like crosslinked structure 13 is shown. It shows a state in which a plurality of dungling chains 14 are bound to the above.
First, the holding force when holding the work 1 on the surface of the non-foamed urethane resin layer 11 is derived from the intermolecular force between the work 1 and the dangling chain 14, and this intermolecular force is extremely about 3 to 5 Å. Works only at close range.
Therefore, when the work 1 is brought into close contact with the non-foaming urethane resin layer 11, the fine irregularities on the surface of the work 1 are made wet by the constituent substances of the non-foaming urethane resin layer 11 to generate a high holding force. be able to.
Here, the dangling chain 14 having one end freed behaves like a liquid, so that the dangling chain 14 can make the surface of the work 1 wet, thereby producing a high holding force. It has become.
Further, when a stress in the horizontal direction acts on the thick portion of the work 1, one end of a part of the dungling chain 14 is separated from the work 1, but one end of the other dungling chain 14 adheres to the work 1. Since the wet state is maintained, the holding power is maintained.
Here, the holding force of the non-foamed urethane resin layer 11 increases or decreases depending on the number of dungling chains 14 connected to the mesh-like crosslinked structure 13, in other words, the holding force of the work 1 is adjusted by the density of the dungling chains 14. It is possible to do.

Next, FIG. 5 schematically shows the action when the work 1 is separated from the non-foamed urethane resin layer 11.
As shown in FIG. 5A, when the work 1 is moved upward, a part of the dungling chains 14 extends straight while the other dungling chains maintain a state of being in close contact with the work 1, so that during that time. Is maintained in a state where the work 1 is held by the non-foamed urethane resin layer 11.
After that, as shown in FIG. 5B, when the work 1 is further moved upward, a part of the dungling chain 14 is fully extended, and the interaction between the work 1 and the dungling chain due to the intermolecular force is released. , The work 1 is separated from the non-foamed urethane resin layer 11.
At this time, the distance on which the dungling chain 14 acts depends on the molecular weight of the dungling chain 14, that is, the adhesive strength can be adjusted by the molecular weight.
Further, when the work 1 is separated from the dungling chain 14, the intermolecular force acting between them is the chemical bond constituting the dungling chain 14 or the urethane of the dungling chain and the network crosslinked structure. Since it is lower than the bond, the dungling chain 14 is not divided, and therefore the adhesive component constituting the non-foamed urethane resin layer 11 does not remain on the work 1.
That is, since the dungling chain 14 is not damaged even if the work 1 is detached, it is possible to hold the new work 1 in the non-foamed urethane resin layer 11 after use.
Further, since the carbon number of the aliphatic group in the diol compound and / or the polyol compound constituting the dungling chain is as large as 10 to 30 and exhibits a large hydrophobicity, water is interposed between the work 1 and the non-foaming polyurethane resin layer 11. The work can be easily separated by making the work.

Next, the foamed resin layer 12 constituting the work holding sheet 7 will be described. A polyurethane foamed resin can be preferably used as the foamed resin layer 12, and a plurality of tear-shaped bubbles are formed inside. preferable. Here, the tear-shaped bubbles are intended to be bubbles formed inside the polyurethane sheet by the wet film forming method.
The foamed resin layer 12 can be formed by a wet film forming method. Here, the wet film forming method is a method in which a resin to be formed is dissolved in an organic solvent, the resin solution is applied to a sheet-like substrate, and then the resin is passed through a coagulating liquid in which the organic solvent is dissolved but the resin is not dissolved. The organic solvent is replaced, coagulated, and dried to form a foamed layer. For example, it can be produced with reference to Japanese Patent No. 5421635 and Japanese Patent No. 5844189.

The type of polyurethane resin constituting the foamed resin layer 12 is not particularly limited, and may be selected from various polyurethane resins according to the purpose of use. For example, polyester-based, polyether-based, polycarbonate-based, or a mixture thereof resin can be used.
The foamed resin layer 12 of this example contains a hard segment component and a soft segment, and the polyurethane resin may contain 30 to 70% by mass of a polyether-based, polyester-based, or polycarbonate-based polyol as a soft segment component. desirable.
By including the soft segment component in the foamed resin layer 12 in the above range, the hydroxyl group (OH) contained in the foamed resin layer 12 and the isocyanate group (NCO) contained in the non-foamed urethane resin layer 11 can be chemically bonded. Even if a horizontal stress acts on the non-foaming urethane resin layer 11 via the work 1 during the polishing operation, delamination between the foamed resin layer 12 and the non-foaming urethane resin layer 11 is prevented.
In particular, when the soft segment component is 30% by mass or more, the hydroxyl group (OH) contained in the foamed resin layer 12 and the isocyanate group (NCO) contained in the non-foamed urethane resin layer 11 are delaminated by a chemical bond. By making it difficult and making it 70% by mass or less, the foamed resin layer 12 can maintain flexibility and disperse the stress acting on the work 1 during the polishing operation.
In the present specification, the soft segment component can be measured by pulse NMR, and pulse NMR can be measured by the solid echo method under the following conditions.
<Conditions for pulse NMR measurement>
Measuring device: JNM-MU25 manufactured by JEOL Ltd., measured magnetic field strength: 0.58T, observation frequency: 25MHz, observation nucleus: 1H, measurement: spin-spin relaxation (T2), measurement method: Solid Echo method, pulse width : 2.2 μs, pulse interval: 13.0 μs, pulse repetition time: 4.0 sec, number of integrations: 16 times, measurement temperature: 20 ° C.

The solid echo method is already well known and details will be omitted, but it is mainly used for measuring samples having a short relaxation time such as glassy and crystalline polymers.
In the 90 ° x-τ-90 ° y pulse method in which two 90 ° pulses are applied with the phase changed by 90 ° by apparently removing the dead time, when a 90 ° pulse is applied in the X-axis direction, the dead time is obtained. Later, a free induction decay (FID) signal is observed.
When a second 90 ° pulse is applied in the y-axis direction to the time τ at which the FID signal is not attenuated, echoes appear with the magnetization directions aligned at t = 2τ. The resulting echo can be approximated to the FID signal after a 90 ° pulse.
A method for analyzing the relationship between physical properties, phase-separated structure, and composition from the analysis results of pulse NMR is already well known, and the spin-spin relaxation time of the free induction decay (FID) signal obtained by pulse NMR is obtained by the minimum square method. By subtracting from the longest component of T2 in order and separating the waveform, it can be divided into three components. The component with a long relaxation time is the component with large motility and the amorphous phase (soft segment component), and the component with short relaxation time is motility. It is defined as a crystal phase (hard segment component), which is a small component of, and an interfacial phase (analyzed as an interfacial phase when it is difficult to separate the components of the interfacial phase and the amorphous phase). The amount of each component is calculated using the formula using the type function.
Regarding the pulse NMR, the solid echo method, and the spin-spin relaxation time T2, Japanese Patent Application Laid-Open No. 2007-238783 (particularly, paragraphs [0028] to [0033]) can be referred to.

Since the foamed resin layer 12 having the above structure is rich in compressibility and recoverability, when the work 1 is pressed by the polishing surface plate 5 and stress acts on the non-foamed urethane resin layer 11 via the work 1, it follows this. While deforming, it contributes to the retention of the work 1.
In particular, when polishing stress acts on the side surface of the work 1, the stress is not concentrated on the non-foamed urethane resin layer 11 but is dispersed in the foamed resin layer 12, so that the work 1 is peeled off from the work holding sheet 7. It is possible to polish the side surface of the work 1 and the curved portion 1a without any problem.
At this time, the work can be held by both the holding power of the work obtained by compressing and deforming the foamed resin layer 12 and following the work and the holding power of the work due to the surface adhesiveness of the non-foamed urethane resin layer 11. Therefore, the adhesive strength of the non-foaming urethane resin layer 11 can be lowered, and the removability of the non-foaming urethane resin layer 11 can be improved accordingly.
Further, since the work holding sheet 7 of this embodiment has a structure in which the non-foamed urethane resin layer 11 and the foamed resin layer 12 are laminated and chemically bonded, the work holding sheet 7 has a structure in which the non-foamed urethane resin layer 11 and the foamed resin layer 12 are chemically bonded to each other in the horizontal direction with respect to the work 1. Even when stress is applied, the non-foamed urethane resin layer 11 and the foamed resin layer 12 are prevented from peeling off.

Hereinafter, a method for manufacturing the work holding sheet 7 of this embodiment will be described.
First, in order to form the urethane resin composition constituting the non-foaming urethane resin layer 11, an isocyanate group-terminated prepolymer, a trifunctional isocyanurate compound, a diol compound that functions as a dungling chain, and / or a trifunctional or higher functional polyol compound. To mix.

As the isocyanate group-terminated prepolymer, an isocyanate group-containing compound prepared by reacting a polyisocyanate compound with a polyol compound (for urethane prepolymer), which is often used in the art, can be used. Moreover, various commercially available urethane prepolymers may be used.
The polyisocyanate compound is not particularly limited, and is, for example, m-phenylenediocyanate, p-phenylenediocyanate, 2,6-tolylene diisocyanate (2,6-TDI), 2,4-tolylene diisocyanate (2,4-). TDI), naphthalene-1,4-diisocyanate, diphenylmethane-4,4'-diisocyanate (MDI), 4,4'-methylene-bis (cyclohexylisocyanate) (hydrogenated MDI), 3,3'-dimethoxy-4, 4'-biphenyldiisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, xylylene-1,4-diisocyanate, 4,4'-diphenylpropanediisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate, propylene-1, 2-diisocyanate, butylene-1,2-diisocyanate, cyclohexylene-1,2-diisocyanate, cyclohexylene-1,4-diisocyanate, p-phenylenediisothiocianate, xylylene-1,4-diisocyanate, etylidinedi Isocyanates and the like can be mentioned.

Examples of the polyol compound for the isocyanate group-terminated prepolymer include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, and 1,4-butanediol. , Neopentyl glycol, pentandiol, 3-methyl-1,5-pentanediol, 1,6-hexanediol and other diols; polyether polyols such as polytetramethylene glycol (PTMG), polyethylene glycol and polypropylene glycol; ethylene glycol Polyethylene polyols such as a reaction product of and adipic acid and a reaction product of butylene glycol and adipic acid; polycarbonate polyol; polycaprolactone polyol; and the like can be mentioned.

Examples of the trifunctional isocyanurate compound include an isocyanurate form of a hexamethylene diisocyanate compound, an isocyanurate form of an isophorone diisocyanate compound, an isocyanurate form of a tolylene diisocyanate compound, an isocyanurate form of a xylylene diisocyanate compound, and a hydrogenated xylylene diisocyanate compound. It is preferable that at least one selected from the group of compounds consisting of isocyanurates.

The diol compound and / or the polyol compound that functions as a dungling chain is not particularly limited as long as it is a polyol having a saturated or unsaturated aliphatic group dungling chain having 10 to 30 carbon atoms.
For example, it may contain a diol compound having a dungling chain of a saturated or unsaturated aliphatic group having 10 to 30 carbon atoms and / or a polyol compound having two or more hydroxyl groups, and has an activity of reacting with other isocyanate groups. An active hydrogen compound having two or more hydrogen groups can also be used in combination.
Specific examples of the diol compound are not particularly limited, but for example, glyceryl caprate, glyceryl laurate, glyceryl myristate, glyceryl pentadecylate, glyceryl palmitate, glyceryl margarate, glyceryl stearate, glyceryl arachidate, glyceryl henicosylate. Glycerin saturated fatty acid esters such as glyceryl behenate, glyceryl lignocerate, glyceryl serotate, glyceryl montanate, glyceryl melisinate; Examples thereof include glycerin unsaturated fatty acid esters such as glyceryl, glyceryl eleostearate, glyceryl arachidate, glyceryl arachidate and glyceryl nervone. Examples of the polyol compound include polyglycerin fatty acid esters such as diglyceryl monooleate and decaglyceryl trioleate.

As the trifunctional or higher functional polyol compound, trimethylolpropane having a molecular weight of 3000 to 6000, pentaerythritol, and polypropylene glycol can be used, and it is desirable that the total amount of the mixed solution is 5 to 20% by mass.

In addition, other additives may be used if necessary. Examples of other additives include silicone defoamers and the like.
The content of the defoaming agent is preferably 0.1 to 3% by mass, more preferably 0.3 to 2.5% by mass, still more preferably 0.5, based on the total amount of the mixed solution. ~ 2.0% by mass. When the content of the defoaming agent is within the above range, the generation of bubbles tends to be further suppressed.

After preparing the mixed solution for forming the non-foaming urethane resin layer 11, the mixed solution for forming the non-foaming urethane resin layer 11 is applied onto the polyurethane resin sheet constituting the foamed resin layer 12 and cured.
For the method of producing the polyurethane resin sheet, refer to Japanese Patent No. 5421635 and Japanese Patent No. 5844189, and after wet-forming the polyurethane resin, the back surface side is buffed and the buffed surface is made of polyethylene terephthalate resin. The sex sheet is attached with an adhesive, and a double-sided tape for adhering to the holding platen 3 is attached to the surface of the flexible sheet where the polyurethane resin sheet is not attached.
Then, a mixed solution for forming the non-foaming urethane resin layer 11 is uniformly applied to the surface of the polyurethane resin sheet, which is the surface opposite to the surface to which the double-sided tape is attached, by a known printing technique typified by screen printing. It is applied to a thickness and then put into an oven for thermosetting.
At this time, a cross-linking reaction occurs to form the network-like cross-linking structure 13, and the dungling chain 14 is bonded to the network-like cross-linking structure 13 to form the non-foamed urethane resin layer 11.
On the other hand, at the boundary between the non-foamed urethane resin layer 11 and the foamed resin layer 12, the hydroxyl group (OH) contained in the foamed resin layer 12 and the isocyanate group (NCO) contained in the non-foamed urethane resin layer 11 are chemically bonded. It has become like.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. The present invention is not limited to the following examples.

[Polishing test]
A plate-shaped carrier for holding the work in a predetermined arrangement was adhered to the front surface of the work holding sheet, and the back surface of the work holding sheet was fixed to the holding surface plate with double-sided tape.
Next, 10 glass substrates (flat surface size 65 mm × 65 mm, thickness 10 mm, curved surface processed at the end) are held inside the carrier holding holes on the work holding sheet and polished under the following conditions. A polishing test was conducted.
In Examples 1 to 6 and Comparative Example 2, the work is directly held between the glass substrate and the work holding sheet without water, and in Comparative Example 1, the surface of the work holding sheet is used to improve the adsorption force. Wet it with water and hold the work through the water.

The polishing device used for polishing uses "Model No .: DSM9B-5P-IV" manufactured by Speedfam, and as a polishing pad, a polishing layer (manufactured by Fujibo Ehime Co., Ltd., product number: 510VL) and a cushion layer (Softlon SX2005; thickness) are used. A laminated polishing pad was used in which 5.0 mm, Shore A hardness 15.0, compressibility 30.0%, manufactured by Sekisui Chemical Co., Ltd.) were bonded with a double-sided tape with a PET core material.
The polishing conditions for polishing were set to a load: 330 gf / cm ² , a polishing speed: top ring 60 rpm / surface plate rotation speed 60 rpm, and polishing time: 1 hour / batch.
Further, as a slurry used for polishing, COMPOLEEX-3 manufactured by Fujimi Incorporated Co., Ltd. was supplied at a slurry flow rate of 5 cc / min (circulation).

[Example 1]
As the polyurethane resin forming the foamed resin layer, a polyester MDI (diphenylmethane diisocyanate) polyurethane resin having a 100% modulus of 10 MPa was used.
Polyurethane is mixed with 100 parts by mass of DMF solution of this polyurethane resin, 45 parts by mass of DMF for viscosity adjustment, 40 parts by mass of DMF dispersion containing 30% of pigment carbon black, and 2 parts by mass of hydrophobic activator. A resin solution was prepared.
The insoluble component was removed by filtering the obtained resin-containing solution. The solution was cast on a polyester sheet using a knife coater so that the coating thickness was 1.2 mm.
Then, the polyester sheet cast with the resin-containing solution is immersed in a coagulation bath (the coagulation liquid is water) to coagulate the resin-containing solution, and then the polyester sheet is peeled off, washed and dried to obtain a polyurethane resin having a thickness of 1 mm. I got a sheet.
The back surface of the obtained polyurethane resin sheet was buffed to a thickness of 0.9 mm, and then a PET resin base material having a thickness of 0.188 μm was bonded to the buffed surface side with an adhesive to obtain a polyurethane foam resin sheet. ..
Subsequently, 50.1 parts by mass of a urethane prepolymer (manufactured by Nippon Polyurethane Co., Ltd., product name DC6912) having an NCO equivalent of 540 containing 2,4-tolylene diisocyanate as a main component was used so that the R value was 1.1. 7 parts by mass of isocyanurate (Coronate HX, manufactured by Tosoh Corporation) of hexamethylene diisocyanate, which is a trifunctional isocyanate compound, polyoxypropylene glycol (manufactured by Sanyo Kasei Co., Ltd., prime pole, OH) having three hydroxyl groups as a trifunctional or higher polyol. Equivalent 1700) 9.1 parts by mass, diglyceryl monooleate (Nikko Chemicals, NIKKOL MGO, OH equivalent 178) 33.7 parts by mass as a dungling chain, and silicone-based antifoaming agent (Tosoh Dow Corning) , 71 ADDITIVE) 0.05 parts by mass was uniformly mixed to obtain a mixed solution.
The above mixed solution was applied onto a polyurethane foamed resin sheet by a screen printing machine so as to have a uniform thickness, and was cured by heating at 80 ° C. for 1 hour to obtain a work holding sheet of Example 1.
The obtained work holding sheet had a non-foamed polyurethane resin layer having a thickness of 30 μm on the polyurethane foamed resin sheet.

[Example 2]
An isocyanurate product of 52.9 parts by mass of urethane prepolymer having an NCO equivalent of 540 containing 2,4-tolylene diisocyanate as a main component and hexamethylene diisocyanate which is a trifunctional isocyanate compound so that the R value is 1.1. (Tosoh Co., Ltd., Coronate HX) 4.24 parts by mass, 12 parts by mass of polyoxypropylene glycol (manufactured by Sanyo Kasei Co., Ltd., prime pole, OH equivalent 1700) having three hydroxyl groups as a trifunctional or higher functional polyol, and a dungling chain 30.78 parts by mass of diglyceryl monooleate (manufactured by Nikko Chemicals, NIKKOL MGO, OH equivalent 178) and 0.05 parts by mass of silicone-based antifoaming agent (manufactured by Toray Dow Corning, 71 ADDITIVE). A work holding sheet was obtained in the same manner as in Example 1 except that the non-foamed urethane resin layer was formed by the mixed solution prepared by uniformly mixing.

[Example 3]
48.14 parts by mass of urethane prepolymer having an NCO equivalent of 540 containing 2,4-tolylene diisocyanate as a main component and isocyanurate of hexamethylene diisocyanate which is a trifunctional isocyanate compound so that the R value is 1.1. (Tosoh Co., Ltd., Coronate HX) 9.00 parts by mass, polyoxypropylene glycol having three hydroxyl groups as a trifunctional or higher functional polyol (Sanyo Kasei Co., Ltd., prime pole, OH equivalent 1700) 6.98 parts by mass and dung As a ring chain, 35.82 parts by mass of diglyceryl monooleate (manufactured by Nikko Chemicals, NIKKOL MGO, OH equivalent 178) and 0.05 parts by mass of silicone-based antifoaming agent (manufactured by Toray Dow Corning, 71 ADDITIVE). , And a non-foamed urethane resin layer was formed by the adjusted mixed solution, and a work holding sheet was obtained in the same manner as in Example 1.

[Example 4]
60.66 parts by mass of urethane prepolymer having an NCO equivalent of 540 containing 2,4-tolylene diisocyanate as a main component and isocyanurate of hexamethylene diisocyanate which is a trifunctional isocyanate compound so that the R value becomes 0.80. (Tosoh Co., Ltd., Coronate HX) 6.01 parts by mass, polyoxypropylene glycol having three hydroxyl groups as a trifunctional or higher functional polyol (Sanyo Kasei Co., Ltd., prime pole, OH equivalent 1700) 5.66 parts by mass and dung As a ring chain, 27.63 parts by mass of diglyceryl monooleate (manufactured by Nikko Chemicals, NIKKOL MGO, OH equivalent 178) and 0.05 parts by mass of silicone-based antifoaming agent (manufactured by Toray Dow Corning, 71 ADDITIVE). , And a non-foamed urethane resin layer was formed by the adjusted mixed solution, and a work holding sheet was obtained in the same manner as in Example 1.

[Example 5]
55.48 parts by mass of urethane prepolymer having an NCO equivalent of 540 containing 2,4-tolylene diisocyanate as a main component and isocyanurate of hexamethylene diisocyanate which is a trifunctional isocyanate compound so that the R value becomes 1.30. (Tosoh Co., Ltd., Coronate HX) 1.66 parts by mass, polyoxypropylene glycol (manufactured by Sanyo Kasei Co., Ltd., prime pole, OH equivalent 1700) 8.00 parts by mass and dung As a ring chain, 34.84 parts by mass of diglyceryl monooleate (manufactured by Nikko Chemicals, NIKKOL MGO, OH equivalent 178) and 0.02 parts by mass of silicone-based antifoaming agent (manufactured by Toray Dow Corning, 71 ADDITIVE). , And a non-foamed urethane resin layer was formed by the adjusted mixed solution, and a work holding sheet was obtained in the same manner as in Example 1.

[Example 6]
58.06 parts by mass of urethane prepolymer having an NCO equivalent of 540 containing 2,4-tolylene diisocyanate as a main component and isocyanurate of hexamethylene diisocyanate which is a trifunctional isocyanate compound so that the R value is 0.71. (Tosoh Co., Ltd., Coronate HX) 9.68 parts by mass, polyoxypropylene glycol having three hydroxyl groups as a trifunctional or higher functional polyol (Sanyo Kasei Co., Ltd., prime pole, OH equivalent 1700) 5.47 parts by mass and dung As a ring chain, 26.74 parts by mass of diglyceryl monooleate (manufactured by Nikko Chemicals, NIKKOL MGO, OH equivalent 178) and 0.05 parts by mass of silicone-based antifoaming agent (manufactured by Toray Dow Corning, 71 ADDITIVE). , And a non-foamed urethane resin layer was formed by the adjusted mixed solution, and a work holding sheet was obtained in the same manner as in Example 1.

[Comparative Example 1]
A work holding sheet of Comparative Example 1 was obtained in the same manner as in Example 1 except that the non-foaming polyurethane resin was not applied. That is, Comparative Example 1 is a work holding sheet made of only a polyurethane foam resin sheet.

[Comparative Example 2]
34.65 parts by mass of urethane prepolymer having an NCO equivalent of 540 containing 2,4-tolylene diisocyanate as a main component and isocyanurate of hexamethylene diisocyanate which is a trifunctional isocyanate compound so that the R value becomes 1.10. (Tosoh Co., Ltd., Coronate HX) 3.6 parts by mass, polyoxypropylene glycol having three hydroxyl groups as a trifunctional or higher functional polyol (Sanyo Kasei Co., Ltd., prime pole, OH equivalent 1700) 26.75 parts by mass, polytetra 34.96 parts by mass of methylene ether glycol (PTMG1000 manufactured by Mitsubishi Chemical Co., Ltd.) and 0.04 parts by mass of silicone-based defoaming agent (71 ADDITIVE manufactured by Toray Dow Corning Co., Ltd.) were uniformly mixed and prepared by a mixed solution. A work holding sheet was obtained in the same manner as in Example 1 except that the non-foamed urethane resin layer was formed.

With respect to Examples 1 to 6 and Comparative Examples 1 and 2, the work adsorption / desorption property of the work holding sheet was evaluated.
Here, the case where the work did not fall off until the end of polishing was evaluated as ◯, and the case where the work fell off by the end of polishing was evaluated as ×.
In the work holding sheets of Examples 1 to 6, the work could be held without shifting until the end of polishing, and the evaluation was 〇 in each case. On the other hand, the work holding sheets of Comparative Examples 1 and 2 could not cope with the stress in the horizontal direction during the polishing process, and all the works came off, so the evaluation was x.
Further, when the work was removed from the holding surface plate 3 after the polishing was completed, the work holding sheets of Examples 1 to 6 could easily take out the work, and no transfer of the adhesive component to the work was found. ..
In Comparative Examples 1 and 2, the removability could not be evaluated because the work had fallen off.

1 Work 2 Polishing device 3 Holding surface plate 4 Polishing pad 5 Polishing surface plate 7 Work holding sheet 11 Non-foamed urethane resin layer 12 Foamed resin layer 13 Reticulated crosslinked structure 14 Dungling chain

Claims (5)

In a work holding sheet having a non-foamed urethane resin layer having a holding surface in close contact with the work and a foamed resin layer bonded to the surface side opposite to the holding surface of the non-foamed urethane resin layer.
The non-foamed urethane resin layer contains a network crosslinked structure in which the isocyanate group-terminated prepolymer is crosslinked with a trifunctional or higher functional polyol compound and a trifunctional isocyanurate compound, and at least a part of the network crosslinked structure is a diol compound and. / Or a workpiece holding sheet to which a dungling chain made of a polyol compound is bonded. The foamed resin layer is made of polyurethane foamed resin.
The work holding sheet according to claim 1, further comprising a soft segment component in a proportion of 30 to 70% by mass. The R value (NCO / OH), which is the equivalent ratio of the isocyanate group-terminated prepolymer to the hydroxyl group of the polyol compound constituting the non-foamed urethane resin layer and the isocyanate group of the trifunctional isocyanurate compound, is 0.7 to 1.3. The work holding sheet according to any one of claims 1 or 2, characterized in that it is a range. The work holding sheet according to any one of claims 1 to 3, wherein the trifunctional isocyanurate is contained in the range of 2 to 20% by mass with respect to the non-foamed urethane resin layer. The work holding sheet according to any one of claims 1 to 4, wherein the diol compound and / or the polyol component is contained in the range of 20 to 45% by mass with respect to the non-foamed urethane resin layer.

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